SAT-3/WASC or South Atlantic 3/West Africa Submarine Cable is a submarine communications cable linking Portugal and Spain to South Africa, with connections to several West African countries along the route. It forms part of the SAT-3 / WASC/SAFE cable system; the SAT-3/WASC/SAFE system provides a path between Asia and Europe for telecommunications traffic, an alternative to the cable routes that pass through the Middle East, such as SEA-ME-WE 3 and FLAG. SAT-3 has a capacity of 340 Gbit/s; the SAT-3 system together with SAFE was built by a consortium of operators. As of 2006, major investors included France Telecom, Nitel. Prices for SAT-3 bandwidth in the African countries it serves are high in large part because operators have monopoly control of access; the lowest rates occur in Ghana, where the Ghana Internet Service Providers Association organized a two-year negotiation with and court fight against Ghana Telecom. SEACOM president Brian Herlihy states that the owners of the SAT-3 cable have cut prices by 50% since the 2007 announcement of Seacom, in order to compete with the arrival of Seacom in East Africa.
The SAT-3 has landing points in European countries: Sesimbra, Portugal Chipiona, Spain Alta Vista, Canary Islandsand in Africa: Dakar, Senegal Abidjan, Côte d'Ivoire Accra, Ghana Cotonou, Benin Lagos, Nigeria Douala, Cameroon Libreville, Gabon Cacuaco, Angola Melkbosstrand, South Africa meeting SAFEAlthough Telecom Namibia holds ownership in SAT-3/WASC, Namibia has no landing point. Namibian internet users have no access to SAT-3/WASC, because Telecom Namibia would have to purchase capacity from Telkom SA, due to Telkom SA's high prices has so far refused to do so; the cable itself consists of four fibers, using Erbium-doped fiber amplifier repeaters and wavelength division multiplexing. SAT-3/WASC/SAFE began operations in 2001, providing the first links to Europe for West African internet users and, for South Africans, taking up service from SAT-2, reaching maximum capacity. SAT-2 had been brought into service in the early 1990s as a replacement for the original undersea cable SAT-1, constructed in the 1960s.
In November 2007, no internet access was available through SAT-3 for about seven days in parts of central Africa. A government official from Cameroon blamed a technical failure at the underwater SAT-3 high sea fibre optic terminal, about forty kilometres from Douala. Many ISPs in Cameroon had transitioned their connections from independent satellite connections to SAT-3 in mid-2007 creating serious communication difficulties during the seven days. In late July 2009, SAT-3 cable damage caused internet blackouts in multiple west African countries including Benin, Togo and Nigeria. Togo and Niger were "completely offline" and Benin was able to "reroute its net traffic through neighboring countries." However, the three nations were able to use alternative satellite links in order to maintain some Internet communication with the rest of the world. Nigeria suffered a 70% loss of bandwidth that caused problems in banking and other mobile networks. President of the Nigeria Internet Group, Lanre Ajayi, said, " a critical national resource because of its importance to the economy and to security."
Two weeks may pass. List of international submarine communications cables Individual cable systems off the coast of Africa include:Atlantis-2 Argentina linked to Portugal EASSy East Africa Cable linking South Africa and East African nations. LION Main One Portugal linked to West Africa SAT-2 Portugal linked to South Africa SEACOM East coast of Africa GLO-1 Nigeria to the UK ACE South Africa linked to France WACS South Africa linked to the United Kingdom Official SAT-3/WASC/SAFE Homepage The Sat3 Fibre - a Monopoly That Stands in the Way of Cheaper International Bandwidth What Must Happen when SAT3’s Monopoly Comes to an End
A mobile phone, cell phone, cellphone, or hand phone, sometimes shortened to mobile, cell or just phone, is a portable telephone that can make and receive calls over a radio frequency link while the user is moving within a telephone service area. The radio frequency link establishes a connection to the switching systems of a mobile phone operator, which provides access to the public switched telephone network. Modern mobile telephone services use a cellular network architecture, therefore, mobile telephones are called cellular telephones or cell phones, in North America. In addition to telephony, 2000s-era mobile phones support a variety of other services, such as text messaging, MMS, Internet access, short-range wireless communications, business applications, video games, digital photography. Mobile phones offering only those capabilities are known as feature phones; the first handheld mobile phone was demonstrated by John F. Mitchell and Martin Cooper of Motorola in 1973, using a handset weighing c. 2 kilograms.
In 1979, Nippon Telegraph and Telephone launched the world's first cellular network in Japan. In 1983, the DynaTAC 8000x was the first commercially available handheld mobile phone. From 1983 to 2014, worldwide mobile phone subscriptions grew to over seven billion—enough to provide one for every person on Earth. In first quarter of 2016, the top smartphone developers worldwide were Samsung and Huawei, smartphone sales represented 78 percent of total mobile phone sales. For feature phones as of 2016, the largest were Samsung and Alcatel. A handheld mobile radio telephone service was envisioned in the early stages of radio engineering. In 1917, Finnish inventor Eric Tigerstedt filed a patent for a "pocket-size folding telephone with a thin carbon microphone". Early predecessors of cellular phones included analog radio communications from trains; the race to create portable telephone devices began after World War II, with developments taking place in many countries. The advances in mobile telephony have been traced in successive "generations", starting with the early zeroth-generation services, such as Bell System's Mobile Telephone Service and its successor, the Improved Mobile Telephone Service.
These 0G systems were not cellular, supported few simultaneous calls, were expensive. The first handheld cellular mobile phone was demonstrated by John F. Mitchell and Martin Cooper of Motorola in 1973, using a handset weighing 2 kilograms; the first commercial automated cellular network analog was launched in Japan by Nippon Telegraph and Telephone in 1979. This was followed in 1981 by the simultaneous launch of the Nordic Mobile Telephone system in Denmark, Finland and Sweden. Several other countries followed in the early to mid-1980s; these first-generation systems could support far more simultaneous calls but still used analog cellular technology. In 1983, the DynaTAC 8000x was the first commercially available handheld mobile phone. In 1991, the second-generation digital cellular technology was launched in Finland by Radiolinja on the GSM standard; this sparked competition in the sector as the new operators challenged the incumbent 1G network operators. Ten years in 2001, the third generation was launched in Japan by NTT DoCoMo on the WCDMA standard.
This was followed by 3.5G, 3G+ or turbo 3G enhancements based on the high-speed packet access family, allowing UMTS networks to have higher data transfer speeds and capacity. By 2009, it had become clear that, at some point, 3G networks would be overwhelmed by the growth of bandwidth-intensive applications, such as streaming media; the industry began looking to data-optimized fourth-generation technologies, with the promise of speed improvements up to ten-fold over existing 3G technologies. The first two commercially available technologies billed as 4G were the WiMAX standard, offered in North America by Sprint, the LTE standard, first offered in Scandinavia by TeliaSonera. 5G is a technology and term used in research papers and projects to denote the next major phase in mobile telecommunication standards beyond the 4G/IMT-Advanced standards. The term 5G is not used in any specification or official document yet made public by telecommunication companies or standardization bodies such as 3GPP, WiMAX Forum or ITU-R.
New standards beyond 4G are being developed by standardization bodies, but they are at this time seen as under the 4G umbrella, not for a new mobile generation. Smartphones have a number of distinguishing features; the International Telecommunication Union measures those with Internet connection, which it calls Active Mobile-Broadband subscriptions. In the developed world, smartphones have now overtaken the usage of earlier mobile systems. However, in the developing world, they account for around 50% of mobile telephony. Feature phone is a term used as a retronym to describe mobile phones which are limited in capabilities in contrast to a modern smartphone. Feature phones provide voice calling and text messaging functionality, in addition to basic multimedia and Internet capabilities, other services offered by the user's wireless service provider. A feature phone has additional functions over and above a basic mobile phone, only capable of voice calling and text messaging. Feature phones and basic mobile phones tend to use a proprietary, custom-designed software and user interface.
By contrast, smartphones use a mobile operating system that shares common traits across devices. There are Orthodox Jewish religious re
Amateur radio known as ham radio, describes the use of radio frequency spectrum for purposes of non-commercial exchange of messages, wireless experimentation, self-training, private recreation, radiosport and emergency communication. The term "amateur" is used to specify "a duly authorised person interested in radioelectric practice with a purely personal aim and without pecuniary interest; the amateur radio service is established by the International Telecommunication Union through the Radio Regulations. National governments regulate technical and operational characteristics of transmissions and issue individual stations licenses with an identifying call sign. Prospective amateur operators are tested for their understanding of key concepts in electronics and the host government's radio regulations. Radio amateurs use a variety of voice, text and data communications modes and have access to frequency allocations throughout the RF spectrum; this enables communication across a city, country, the world, or into space.
In many countries, amateur radio operators may send, receive, or relay radio communications between computers or transceivers connected to secure virtual private networks on the Internet. Amateur radio is represented and coordinated by the International Amateur Radio Union, organized in three regions and has as its members the national amateur radio societies which exist in most countries. According to an estimate made in 2011 by the American Radio Relay League, two million people throughout the world are involved with amateur radio. About 830,000 amateur radio stations are located in IARU Region 2 followed by IARU Region 3 with about 750,000 stations. A smaller number, about 400,000, are located in IARU Region 1; the origins of amateur radio can be traced to the late 19th century, but amateur radio as practiced today began in the early 20th century. The First Annual Official Wireless Blue Book of the Wireless Association of America, produced in 1909, contains a list of amateur radio stations.
This radio callbook lists wireless telegraph stations in Canada and the United States, including 89 amateur radio stations. As with radio in general, amateur radio was associated with various amateur experimenters and hobbyists. Amateur radio enthusiasts have contributed to science, engineering and social services. Research by amateur operators has founded new industries, built economies, empowered nations, saved lives in times of emergency. Ham radio can be used in the classroom to teach English, map skills, math and computer skills; the term "ham" was first a pejorative term used in professional wired telegraphy during the 19th century, to mock operators with poor Morse code sending skills. This term continued to be used after the invention of radio and the proliferation of amateur experimentation with wireless telegraphy; the use of "ham" meaning "amateurish or unskilled" survives today in other disciplines. The amateur radio community subsequently began to reclaim the word as a label of pride, by the mid-20th century it had lost its pejorative meaning.
Although not an acronym, it is mistakenly written as "HAM" in capital letters. The many facets of amateur radio attract practitioners with a wide range of interests. Many amateurs begin with a fascination of radio communication and combine other personal interests to make pursuit of the hobby rewarding; some of the focal areas amateurs pursue include radio contesting, radio propagation study, public service communication, technical experimentation, computer networking. Amateur radio operators use various modes of transmission to communicate; the two most common modes for voice transmissions are single sideband. FM offers high quality audio signals, while SSB is better at long distance communication when bandwidth is restricted. Radiotelegraphy using Morse code known as "CW" from "continuous wave", is the wireless extension of landline telegraphy developed by Samuel Morse and dates to the earliest days of radio. Although computer-based modes and methods have replaced CW for commercial and military applications, many amateur radio operators still enjoy using the CW mode—particularly on the shortwave bands and for experimental work, such as earth-moon-earth communication, because of its inherent signal-to-noise ratio advantages.
Morse, using internationally agreed message encodings such as the Q code, enables communication between amateurs who speak different languages. It is popular with homebrewers and in particular with "QRP" or very-low-power enthusiasts, as CW-only transmitters are simpler to construct, the human ear-brain signal processing system can pull weak CW signals out of the noise where voice signals would be inaudible. A similar "legacy" mode popular with home constructors is amplitude modulation, pursued by many vintage amateur radio enthusiasts and aficionados of vacuum tube technology. Demonstrating a proficiency in Morse code was for many years a requirement to obtain an amateur license to transmit on frequencies below 30 MHz. Following changes in international regulations in 2003, countries are no longer required to demand proficiency; the United States Federal
Asia is Earth's largest and most populous continent, located in the Eastern and Northern Hemispheres. It shares the continental landmass of Eurasia with the continent of Europe and the continental landmass of Afro-Eurasia with both Europe and Africa. Asia covers an area of 44,579,000 square kilometres, about 30% of Earth's total land area and 8.7% of the Earth's total surface area. The continent, which has long been home to the majority of the human population, was the site of many of the first civilizations. Asia is notable for not only its overall large size and population, but dense and large settlements, as well as vast populated regions, its 4.5 billion people constitute 60% of the world's population. In general terms, Asia is bounded on the east by the Pacific Ocean, on the south by the Indian Ocean, on the north by the Arctic Ocean; the border of Asia with Europe is a historical and cultural construct, as there is no clear physical and geographical separation between them. It has moved since its first conception in classical antiquity.
The division of Eurasia into two continents reflects East–West cultural and ethnic differences, some of which vary on a spectrum rather than with a sharp dividing line. The most accepted boundaries place Asia to the east of the Suez Canal separating it from Africa. China and India alternated in being the largest economies in the world from 1 to 1800 CE. China was a major economic power and attracted many to the east, for many the legendary wealth and prosperity of the ancient culture of India personified Asia, attracting European commerce and colonialism; the accidental discovery of a trans-Atlantic route from Europe to America by Columbus while in search for a route to India demonstrates this deep fascination. The Silk Road became the main east–west trading route in the Asian hinterlands while the Straits of Malacca stood as a major sea route. Asia has exhibited economic dynamism as well as robust population growth during the 20th century, but overall population growth has since fallen. Asia was the birthplace of most of the world's mainstream religions including Hinduism, Judaism, Buddhism, Taoism, Islam, Sikhism, as well as many other religions.
Given its size and diversity, the concept of Asia—a name dating back to classical antiquity—may have more to do with human geography than physical geography. Asia varies across and within its regions with regard to ethnic groups, environments, historical ties and government systems, it has a mix of many different climates ranging from the equatorial south via the hot desert in the Middle East, temperate areas in the east and the continental centre to vast subarctic and polar areas in Siberia. The boundary between Asia and Africa is the Red Sea, the Gulf of Suez, the Suez Canal; this makes Egypt a transcontinental country, with the Sinai peninsula in Asia and the remainder of the country in Africa. The border between Asia and Europe was defined by European academics; the Don River became unsatisfactory to northern Europeans when Peter the Great, king of the Tsardom of Russia, defeating rival claims of Sweden and the Ottoman Empire to the eastern lands, armed resistance by the tribes of Siberia, synthesized a new Russian Empire extending to the Ural Mountains and beyond, founded in 1721.
The major geographical theorist of the empire was a former Swedish prisoner-of-war, taken at the Battle of Poltava in 1709 and assigned to Tobolsk, where he associated with Peter's Siberian official, Vasily Tatishchev, was allowed freedom to conduct geographical and anthropological studies in preparation for a future book. In Sweden, five years after Peter's death, in 1730 Philip Johan von Strahlenberg published a new atlas proposing the Urals as the border of Asia. Tatishchev announced; the latter had suggested the Emba River as the lower boundary. Over the next century various proposals were made until the Ural River prevailed in the mid-19th century; the border had been moved perforce from the Black Sea to the Caspian Sea into which the Ural River projects. The border between the Black Sea and the Caspian is placed along the crest of the Caucasus Mountains, although it is sometimes placed further north; the border between Asia and the region of Oceania is placed somewhere in the Malay Archipelago.
The Maluku Islands in Indonesia are considered to lie on the border of southeast Asia, with New Guinea, to the east of the islands, being wholly part of Oceania. The terms Southeast Asia and Oceania, devised in the 19th century, have had several vastly different geographic meanings since their inception; the chief factor in determining which islands of the Malay Archipelago are Asian has been the location of the colonial possessions of the various empires there. Lewis and Wigen assert, "The narrowing of'Southeast Asia' to its present boundaries was thus a gradual process." Geographical Asia is a cultural artifact of European conceptions of the world, beginning with the Ancient Greeks, being imposed onto other cultures, an imprecise concept causing endemic contention about what it means. Asia does not correspond to the cultural borders of its various types of constituents. From the time of Herodotus a minority of geographers have rejected the three-continent system on the grounds that there is no substantial physical separation between
An Internet café is a café that provides Internet access to the public. The fee for using a computer is charged as a time-based rate; the first online café in South Korea called Electronic Café opened in front of Hongik University in March 1988 by Ahn Sang-Su and Keum Nuri in Seoul. It had two 16bit computers connected to Online service networks through telephone lines. Online service users’ offline meetings were held in the Electronic Café, which served as a place that connected online and offline activities; the opening of the online café in Korea was 2–3 years ahead of other countries. The online café phenomenon in the United States was started in July 1991 by Wayne Gregori in San Francisco when he began SFnet Coffeehouse Network. Gregori designed and installed 25 coin-operated computer terminals in coffeehouses throughout the San Francisco Bay Area; the café terminals dialed into a 32 line Bulletin Board System that offered an array of electronic services including FIDOnet mail and, in 1992, Internet mail.
The concept of a café with full Internet access was invented in early 1994 by Ivan Pope. Commissioned to develop an Internet event for an arts weekend at the Institute of Contemporary Arts in London, inspired by the SFnet terminal based cafes, Pope wrote a proposal outlining the concept of a café with Internet access. After an initial run in late 1993 as a café showcasing computers, a bar called CompuCafé was established in Helsinki, Finland in the spring of 1994 featuring both Internet access and a robotic beer seller. Around June 1994, The Binary Cafe, Canada's first Internet café, opened in Ontario. Inspired by the ICA event, a commercial establishment of this type, called Cyberia, opened on September 1, 1994, in London, England. In January 1995, CB1 Café in Cambridge, installed an Internet connection and is the longest running Internet Café in the UK, still operating today; the first public, commercial American Internet café was conceived and opened by Jeff Anderson and Alan Weinkrantz in August 1994, at Infomart in Dallas and was called The High Tech Cafe.
The Scottish Bar is the first Internet café in French-speaking Switzerland, connected on June 27, 1995, by Pierre Hemmer and his company MC Management & Communication. Three Internet cafés subsequently opened in the East Village neighborhood of New York City: Internet Cafe, opened by Arthur Perley, the @Cafe, the Heroic Sandwich. In 1996, the Internet café Surf City opened in downtown Alaska. A variation of Internet café called PC bang became popular in South Korea when StarCraft was released in 1998. Although computer and broadband penetration per capita were high, young people went to PC bangs to play multiplayer games. Internet cafés are located worldwide, many people use them when traveling to access webmail and instant messaging services to keep in touch with family and friends. Apart from travelers, in many developing countries Internet cafés are the primary form of Internet access for citizens as a shared-access model is more affordable than personal ownership of equipment and/or software.
A variation on the Internet café business model is the LAN gaming center, used for multiplayer gaming. These cafés have several computer stations connected to a LAN; the connected computers are custom-assembled for gameplay, supporting popular multiplayer games. This is reducing the need for video arcades and arcade games, many of which are being closed down or merged into Internet cafés; the use of Internet cafés for multiplayer gaming is popular in certain areas of Asia like India, Taiwan, Hong Kong, South Korea and the Philippines. In some countries, since all LAN gaming centers offer Internet access, the terms net cafe and LAN gaming center have become interchangeable. Again, this shared-access model is more affordable than personal ownership of equipment and/or software since games require high end and expensive PCs. There are Internet kiosks, Internet access points in public places like public libraries, airport halls, sometimes just for brief use while standing. Many hotels and cruise ships offer Internet access for the convenience of their guests.
As with telephone service, in the US most mid-price hotels offer Internet access from a computer in the lobby to registered guests without charging an additional fee, while fancier hotels are more to charge for the use of a computer in their "business center." For those traveling by road in North America, many truck stops have Internet kiosks, for which a typical charge is around 20 cents per minute. Internet cafés come in a wide range of styles, reflecting their location, main clientele, sometimes, the social agenda of the proprietors. In the early days they were important in projecting the image of the Internet as a'cool' phenomenon. Internet cafés are a natural evolution of the traditional café. Cafés started as places for information exchange, have always been used as places to read the paper, send postcards home, play traditional or electronic games, chat to friends, find out local information; as Internet access is in increasing demand, many pubs and cafés have terminals, so the distinction between the Internet café and normal café is eroded.
In some European countries, the number of pure Internet cafés is decreasing since more and more normal cafés offer the same services. H
In radio communications, a radio receiver known as a receiver, wireless or radio is an electronic device that receives radio waves and converts the information carried by them to a usable form. It is used with an antenna; the antenna intercepts radio waves and converts them to tiny alternating currents which are applied to the receiver, the receiver extracts the desired information. The receiver uses electronic filters to separate the desired radio frequency signal from all the other signals picked up by the antenna, an electronic amplifier to increase the power of the signal for further processing, recovers the desired information through demodulation; the information produced by the receiver may be in the form of sound, moving data. A radio receiver may be a separate piece of electronic equipment, or an electronic circuit within another device. Radio receivers are widely used in modern technology, as components of communications, remote control, wireless networking systems. In consumer electronics, the terms radio and radio receiver are used for receivers designed to reproduce sound transmitted by radio broadcasting stations the first mass-market commercial radio application.
The most familiar form of radio receiver is a broadcast receiver just called a radio, which receives audio programs intended for public reception transmitted by local radio stations. The sound is reproduced either by a loudspeaker in the radio or an earphone which plugs into a jack on the radio; the radio requires electric power, provided either by batteries inside the radio or a power cord which plugs into an electric outlet. All radios have a volume control to adjust the loudness of the audio, some type of "tuning" control to select the radio station to be received. Modulation is the process of adding information to a radio carrier wave. Two types of modulation are used in analog radio broadcasting systems. In amplitude modulation the strength of the radio signal is varied by the audio signal. AM broadcasting is allowed in the AM broadcast bands which are between 148 and 283 kHz in the longwave range, between 526 and 1706 kHz in the medium frequency range of the radio spectrum. AM broadcasting is permitted in shortwave bands, between about 2.3 and 26 MHz, which are used for long distance international broadcasting.
In frequency modulation the frequency of the radio signal is varied by the audio signal. FM broadcasting is permitted in the FM broadcast bands between about 65 and 108 MHz in the high frequency range; the exact frequency ranges vary somewhat in different countries. FM stereo radio stations broadcast in stereophonic sound, transmitting two sound channels representing left and right microphones. A stereo receiver contains the additional circuits and parallel signal paths to reproduce the two separate channels. A monaural receiver, in contrast, only receives a single audio channel, a combination of the left and right channels. While AM stereo transmitters and receivers exist, they have not achieved the popularity of FM stereo. Most modern radios are "AM/FM" radios, are able to receive both AM and FM radio stations, have a switch to select which band to receive. Digital audio broadcasting is an advanced radio technology which debuted in some countries in 1998 that transmits audio from terrestrial radio stations as a digital signal rather than an analog signal as AM and FM do.
Its advantages are that DAB has the potential to provide higher quality sound than FM, has greater immunity to radio noise and interference, makes better use of scarce radio spectrum bandwidth, provides advanced user features such as electronic program guide, sports commentaries, image slideshows. Its disadvantage is that it is incompatible with previous radios so that a new DAB receiver must be purchased; as of 2017, 38 countries offer DAB, with 2,100 stations serving listening areas containing 420 million people. Most countries plan an eventual switchover from FM to DAB; the United States and Canada have chosen not to implement DAB. DAB radio stations work differently from AM or FM stations: a single DAB station transmits a wide 1,500 kHz bandwidth signal that carries from 9 to 12 channels from which the listener can choose. Broadcasters can transmit a channel at a range of different bit rates, so different channels can have different audio quality. In different countries DAB stations broadcast in either Band L band.
The signal strength of radio waves decreases the farther they travel from the transmitter, so a radio station can only be received within a limited range of its transmitter. The range depends on the power of the transmitter, the sensitivity of the receiver and internal noise, as well as any geographical obstructions such as hills between transmitter and receiver. AM broadcast band radio waves travel as ground waves which follow the contour of the Earth, so AM radio stations can be reliably received at hundreds of miles distance. Due to their higher frequency, FM band radio signals cannot travel far beyond the visual horizon; however FM radio has higher fidelity. So in many countries serious music is only broadcast by FM stations, AM stations specialize in radio news, talk radio, sports. Like FM, DAB signals travel by line of sight so reception distances are
The Atlantic Ocean is the second largest of the world's oceans, with an area of about 106,460,000 square kilometers. It covers 20 percent of the Earth's surface and about 29 percent of its water surface area, it separates the "Old World" from the "New World". The Atlantic Ocean occupies an elongated, S-shaped basin extending longitudinally between Europe and Africa to the east, the Americas to the west; as one component of the interconnected global ocean, it is connected in the north to the Arctic Ocean, to the Pacific Ocean in the southwest, the Indian Ocean in the southeast, the Southern Ocean in the south. The Equatorial Counter Current subdivides it into the North Atlantic Ocean and the South Atlantic Ocean at about 8°N. Scientific explorations of the Atlantic include the Challenger expedition, the German Meteor expedition, Columbia University's Lamont-Doherty Earth Observatory and the United States Navy Hydrographic Office; the oldest known mentions of an "Atlantic" sea come from Stesichorus around mid-sixth century BC: Atlantikoi pelágei and in The Histories of Herodotus around 450 BC: Atlantis thalassa where the name refers to "the sea beyond the pillars of Heracles", said to be part of the sea that surrounds all land.
Thus, on one hand, the name refers to Atlas, the Titan in Greek mythology, who supported the heavens and who appeared as a frontispiece in Medieval maps and lent his name to modern atlases. On the other hand, to early Greek sailors and in Ancient Greek mythological literature such as the Iliad and the Odyssey, this all-encompassing ocean was instead known as Oceanus, the gigantic river that encircled the world. In contrast, the term "Atlantic" referred to the Atlas Mountains in Morocco and the sea off the Strait of Gibraltar and the North African coast; the Greek word thalassa has been reused by scientists for the huge Panthalassa ocean that surrounded the supercontinent Pangaea hundreds of millions of years ago. The term "Aethiopian Ocean", derived from Ancient Ethiopia, was applied to the Southern Atlantic as late as the mid-19th century. During the Age of Discovery, the Atlantic was known to English cartographers as the Great Western Ocean; the term The Pond is used by British and American speakers in context to the Atlantic Ocean, as a form of meiosis, or sarcastic understatement.
The term dates to as early as 1640, first appearing in print in pamphlet released during the reign of Charles I, reproduced in 1869 in Nehemiah Wallington's Historical Notices of Events Occurring Chiefly in The Reign of Charles I, where "great Pond" is used in reference to the Atlantic Ocean by Francis Windebank, Charles I's Secretary of State. The International Hydrographic Organization defined the limits of the oceans and seas in 1953, but some of these definitions have been revised since and some are not used by various authorities and countries, see for example the CIA World Factbook. Correspondingly, the extent and number of oceans and seas varies; the Atlantic Ocean is bounded on the west by South America. It connects to the Arctic Ocean through the Denmark Strait, Greenland Sea, Norwegian Sea and Barents Sea. To the east, the boundaries of the ocean proper are Europe: the Strait of Africa. In the southeast, the Atlantic merges into the Indian Ocean; the 20° East meridian, running south from Cape Agulhas to Antarctica defines its border.
In the 1953 definition it extends south to Antarctica, while in maps it is bounded at the 60° parallel by the Southern Ocean. The Atlantic has irregular coasts indented by numerous bays and seas; these include the Baltic Sea, Black Sea, Caribbean Sea, Davis Strait, Denmark Strait, part of the Drake Passage, Gulf of Mexico, Labrador Sea, Mediterranean Sea, North Sea, Norwegian Sea all of the Scotia Sea, other tributary water bodies. Including these marginal seas the coast line of the Atlantic measures 111,866 km compared to 135,663 km for the Pacific. Including its marginal seas, the Atlantic covers an area of 106,460,000 km2 or 23.5% of the global ocean and has a volume of 310,410,900 km3 or 23.3% of the total volume of the earth's oceans. Excluding its marginal seas, the Atlantic covers 81,760,000 km2 and has a volume of 305,811,900 km3; the North Atlantic covers 41,490,000 km2 and the South Atlantic 40,270,000 km2. The average depth is 3,646 m and the maximum depth, the Milwaukee Deep in the Puerto Rico Trench, is 8,486 m.
The bathymetry of the Atlantic is dominated by a submarine mountain range called the Mid-Atlantic Ridge. It runs from 87°N or 300 km south of the North Pole to the subantarctic Bouvet Island at 42°S; the MAR divides the Atlantic longitudinally into two halves, in each of which a series of basins are delimited by secondary, transverse ridges. The MAR reaches above 2,000 m along most of its length, but is interrupted by larger transform faults at two places: the Romanche Trench near the Equator and the Gibbs Fracture Zone at 53°N; the MAR is a barrier for bottom water, but at these two transform faults deep water currents can pass from one side to the othe