Tin is a chemical element with the symbol Sn and atomic number 50. It is a post-transition metal in group 14 of the periodic table of elements, it is obtained chiefly from the mineral cassiterite, which contains stannic oxide, SnO2. Tin shows a chemical similarity to both of its neighbors in group 14, germanium and lead, has two main oxidation states, +2 and the more stable +4. Tin is the 49th most abundant element and has, with 10 stable isotopes, the largest number of stable isotopes in the periodic table, thanks to its magic number of protons, it has two main allotropes: at room temperature, the stable allotrope is β-tin, a silvery-white, malleable metal, but at low temperatures it transforms into the less dense grey α-tin, which has the diamond cubic structure. Metallic tin does not oxidize in air; the first tin alloy used on a large scale was bronze, made of 1/8 tin and 7/8 copper, from as early as 3000 BC. After 600 BC, pure metallic tin was produced. Pewter, an alloy of 85–90% tin with the remainder consisting of copper and lead, was used for flatware from the Bronze Age until the 20th century.
In modern times, tin is used in many alloys, most notably tin/lead soft solders, which are 60% or more tin, in the manufacture of transparent, electrically conducting films of indium tin oxide in optoelectronic applications. Another large application for tin is corrosion-resistant tin plating of steel; because of the low toxicity of inorganic tin, tin-plated steel is used for food packaging as tin cans. However, some organotin compounds can be as toxic as cyanide. Tin is a soft, malleable and crystalline silvery-white metal; when a bar of tin is bent, a crackling sound known as the "tin cry" can be heard from the twinning of the crystals. Tin melts at low temperatures of about 232 °C, the lowest in group 14; the melting point is further lowered to 177.3 °C for 11 nm particles. Β-tin, stable at and above room temperature, is malleable. In contrast, α-tin, stable below 13.2 °C, is brittle. Α-tin has a diamond cubic crystal structure, similar to silicon or germanium. Α-tin has no metallic properties at all because its atoms form a covalent structure in which electrons cannot move freely.
It is a dull-gray powdery material with no common uses other than a few specialized semiconductor applications. These two allotropes, α-tin and β-tin, are more known as gray tin and white tin, respectively. Two more allotropes, γ and σ, exist at temperatures above 161 pressures above several GPa. In cold conditions, β-tin tends to transform spontaneously into α-tin, a phenomenon known as "tin pest". Although the α-β transformation temperature is nominally 13.2 °C, impurities lower the transition temperature well below 0 °C and, on the addition of antimony or bismuth, the transformation might not occur at all, increasing the durability of the tin. Commercial grades of tin resist transformation because of the inhibiting effect of the small amounts of bismuth, antimony and silver present as impurities. Alloying elements such as copper, bismuth and silver increase its hardness. Tin tends rather to form hard, brittle intermetallic phases, which are undesirable, it does not form wide solid solution ranges in other metals in general, few elements have appreciable solid solubility in tin.
Simple eutectic systems, occur with bismuth, lead and zinc. Tin was one of the first superconductors to be studied. Tin can be attacked by acids and alkalis. Tin can be polished and is used as a protective coat for other metals. A protective oxide layer prevents further oxidation, the same that forms on pewter and other tin alloys. Tin helps to accelerate the chemical reaction. Tin has ten stable isotopes, with atomic masses of 112, 114 through 120, 122 and 124, the greatest number of any element. Of these, the most abundant are 120Sn, 118Sn, 116Sn, while the least abundant is 115Sn; the isotopes with mass numbers have no nuclear spin, while those with odd have a spin of +1/2. Tin, with its three common isotopes 116Sn, 118Sn and 120Sn, is among the easiest elements to detect and analyze by NMR spectroscopy, its chemical shifts are referenced against SnMe4; this large number of stable isotopes is thought to be a direct result of the atomic number 50, a "magic number" in nuclear physics. Tin occurs in 29 unstable isotopes, encompassing all the remaining atomic masses from 99 to 137.
Apart from 126Sn, with a half-life of 230,000 years, all the radioisotopes have a half-life of less than a year. The radioactive 100Sn, discovered in 1994, 132Sn are one of the few nuclides with a "doubly magic" nucleus: despite being unstable, having lopsided proton–neutron ratios, they represent endpoints beyond which stability drops off rapidly. Another 30 metastable isomers have been characterized for isotopes between 111 and 131, the most stable being 121mSn with a half-life of 43.9 years. The relative differences in the abundances of tin's stable isotopes can be explained by their different modes of formation in stellar nucleosynthesis. 116Sn through 120Sn inclusive are formed in the s-process in most stars and hence they are the most common isotopes, while 122Sn and 124Sn are only formed in the r-process (rapid neutr
Christian Democratic Union of Germany
The Christian Democratic Union of Germany is a Christian-democratic, liberal-conservative political party in Germany. It is the major catch-all party of the centre-right in German politics; the CDU forms the CDU/CSU grouping known as the Union, in the Bundestag with its Bavarian counterpart the Christian Social Union in Bavaria. The party is considered an effective successor of the Centre Party, although it has a broader base; the leader of the CDU is Annegret Kramp-Karrenbauer. She is the successor of the former party leader Angela Merkel, the current Chancellor of Germany; the CDU is a member of the Centrist Democrat International, International Democrat Union and European People's Party. Following the collapse of the Nazi dictatorship at the end of World War II, the need for a new political order in Germany was paramount. Simultaneous yet unrelated meetings began occurring throughout Germany, each with the intention of planning a Christian-democratic party; the CDU was established in Berlin on 26 June 1945 and in Rheinland and Westfalen in September of the same year.
The founding members of the CDU consisted of former members of the Centre Party, the German Democratic Party, the German National People's Party and the German People's Party. Many of these individuals, including CDU-Berlin founder Andreas Hermes, were imprisoned for the involvement in the German Resistance during the Nazi dictatorship. In the Cold War years after World War II up to the 1960s, the CDU attracted conservative, anti-communist former Nazis and Nazi collaborators into its higher ranks. A prominent anti-Nazi member was theologian Eugen Gerstenmaier, who became Acting Chairman of the Foreign Board. One of the lessons learned from the failure of the Weimar Republic was that disunity among the democratic parties allowed for the rise of the Nazi Party, it was therefore crucial to create a unified party of Christian democrats—a Christian Democratic Union. The result of these meetings was the establishment of an interconfessional party influenced by the political tradition of liberal conservatism.
The CDU experienced considerable success gaining support from the time of its creation in Berlin on 26 June 1945 until its first convention on 21 October 1950, at which Chancellor Konrad Adenauer was named the first Chairman of the party. In the beginning, it was not clear which party would be favored by the victors of World War II, but by the end of the 1940s the governments of the United States and of Britain began to lean toward the CDU and away from the Social Democratic Party of Germany; the latter was more nationalist and sought German reunification at the expense of concessions to the Soviet Union, depicting Adenauer as an instrument of both the Americans and the Vatican. The Western powers appreciated the CDU's moderation, its economic flexibility and its value as an oppositional force to the communists which appealed to European voters at the time. Adenauer was trusted by the British; the party was split over issues of rearmament within the Western alliance and German unification as a neutral state.
Adenauer staunchly outmanoeuvred some of his opponents. He refused to consider the SPD as a party of the coalition until he felt sure that they shared his anti-communist position; the principled rejection of a reunification that would alienate Germany from the Western alliance made it harder to attract Protestant voters to the party as most refugees from the former German territories east of the Oder were of that faith as were the majority of the inhabitants of East Germany. The CDU was the dominant party for the first two decades following the establishment of West Germany in 1949. Adenauer remained the party's leader until 1963, at which point the former minister of economics Ludwig Erhard replaced him; as the Free Democratic Party withdrew from the governing coalition in 1966 due to disagreements over fiscal and economic policy, Erhard was forced to resign. A grand coalition with the SPD took over government under CDU Chancellor Kurt Georg Kiesinger; the SPD gained popularity and succeeded in forming a social-liberal coalition with the FDP following the 1969 federal election, forcing the CDU out of power for the first time in their history.
The CDU continued its role as opposition until 1982, when the FDP's withdrawal from the coalition with the SPD allowed the CDU to regain power. CDU Chairman Helmut Kohl became the new Chancellor of West Germany and his CDU–FDP coalition was confirmed in the 1983 federal election. Public support for the coalition's work in the process of German reunification was reiterated in the 1990 federal election in which the CDU–FDP governing coalition experienced a clear victory. After the collapse of the East German government in 1989, Kohl—supported by the governments of the United States and reluctantly by those of France and the United Kingdom—called for German reunification. On 3 October 1990, the government of East Germany was abolished and its territory acceded to the scope of the Basic Law in place in West Germany; the East German CDU merged with its West German counterpart and elections were held for the reunified country. Although Kohl was re-elected, the party began losing much of its popularity because of an economic recession in the former GDR and increased taxes in the west.
The CDU was nonetheless able to win the 1994 federal election by a narrow margin due to an economic recovery. Kohl served as chairman until the party's electoral defeat in 1998, when he was su
World War I
World War I known as the First World War or the Great War, was a global war originating in Europe that lasted from 28 July 1914 to 11 November 1918. Contemporaneously described as "the war to end all wars", it led to the mobilisation of more than 70 million military personnel, including 60 million Europeans, making it one of the largest wars in history, it is one of the deadliest conflicts in history, with an estimated nine million combatants and seven million civilian deaths as a direct result of the war, while resulting genocides and the 1918 influenza pandemic caused another 50 to 100 million deaths worldwide. On 28 June 1914, Gavrilo Princip, a Bosnian Serb Yugoslav nationalist, assassinated the Austro-Hungarian heir Archduke Franz Ferdinand in Sarajevo, leading to the July Crisis. In response, on 23 July Austria-Hungary issued an ultimatum to Serbia. Serbia's reply failed to satisfy the Austrians, the two moved to a war footing. A network of interlocking alliances enlarged the crisis from a bilateral issue in the Balkans to one involving most of Europe.
By July 1914, the great powers of Europe were divided into two coalitions: the Triple Entente—consisting of France and Britain—and the Triple Alliance of Germany, Austria-Hungary and Italy. Russia felt it necessary to back Serbia and, after Austria-Hungary shelled the Serbian capital of Belgrade on the 28th, partial mobilisation was approved. General Russian mobilisation was announced on the evening of 30 July; when Russia failed to comply, Germany declared war on 1 August in support of Austria-Hungary, with Austria-Hungary following suit on 6th. German strategy for a war on two fronts against France and Russia was to concentrate the bulk of its army in the West to defeat France within four weeks shift forces to the East before Russia could mobilise. On 2 August, Germany demanded free passage through Belgium, an essential element in achieving a quick victory over France; when this was refused, German forces invaded Belgium on 3 August and declared war on France the same day. On 12 August and France declared war on Austria-Hungary.
In November 1914, the Ottoman Empire entered the war on the side of the Alliance, opening fronts in the Caucasus and the Sinai Peninsula. The war was fought in and drew upon each power's colonial empire as well, spreading the conflict to Africa and across the globe; the Entente and its allies would become known as the Allied Powers, while the grouping of Austria-Hungary and their allies would become known as the Central Powers. The German advance into France was halted at the Battle of the Marne and by the end of 1914, the Western Front settled into a battle of attrition, marked by a long series of trench lines that changed little until 1917. In 1915, Italy opened a front in the Alps. Bulgaria joined the Central Powers in 1915 and Greece joined the Allies in 1917, expanding the war in the Balkans; the United States remained neutral, although by doing nothing to prevent the Allies from procuring American supplies whilst the Allied blockade prevented the Germans from doing the same the U. S. became an important supplier of war material to the Allies.
After the sinking of American merchant ships by German submarines, the revelation that the Germans were trying to incite Mexico to make war on the United States, the U. S. declared war on Germany on 6 April 1917. Trained American forces would not begin arriving at the front in large numbers until mid-1918, but the American Expeditionary Force would reach some two million troops. Though Serbia was defeated in 1915, Romania joined the Allied Powers in 1916 only to be defeated in 1917, none of the great powers were knocked out of the war until 1918; the 1917 February Revolution in Russia replaced the Tsarist autocracy with the Provisional Government, but continuing discontent at the cost of the war led to the October Revolution, the creation of the Soviet Socialist Republic, the signing of the Treaty of Brest-Litovsk by the new government in March 1918, ending Russia's involvement in the war. This allowed the transfer of large numbers of German troops from the East to the Western Front, resulting in the German March 1918 Offensive.
This offensive was successful, but the Allies rallied and drove the Germans back in their Hundred Days Offensive. Bulgaria was the first Central Power to sign an armistice—the Armistice of Salonica on 29 September 1918. On 30 October, the Ottoman Empire capitulated. On 4 November, the Austro-Hungarian empire agreed to the Armistice of Villa Giusti after being decisively defeated by Italy in the Battle of Vittorio Veneto. With its allies defeated, revolution at home, the military no longer willing to fight, Kaiser Wilhelm abdicated on 9 November and Germany signed an armistice on 11 November 1918. World War I was a significant turning point in the political, cultural and social climate of the world; the war and its immediate aftermath sparked numerous uprisings. The Big Four (Britain, the United States, It
Breitenbrunn is a community in the Ore Mountains in the district of Erzgebirgskreis in the Free State of Saxony in Germany. The community consists of Breitenbrunn with Breitenhof, Carolathal and Rabenberg, Antonsthal with Antonshöhe, Steinheidel and Fällbach as well as Rittersgrün and Tellerhäuser. Bordering on Breitenbrunn are Johanngeorgenstadt, the health resort of Oberwiesenthal and the town of Schwarzenberg, all in the Erzgebirgskreis. Breitenbrunn lies on a mountain ridge stretching from the Schwarzwasser Valley on east, it is surrounded by, among other mountains, the Sauberg. As the highest village in the lordly domain of Schwarzenberg, Breitenbrunn was founded only in the 13th century. With the help of vast meadows and sites it can be ascertained that no more than ten families settled here at first; the village had its first documentary mention as “breitinprun” in 1380 in a chronicle of the mountain counts of Leisnig when the mining rights for a tin mine had just been granted. Before Breitenbrunn’s founding there was over the site of the settlement a wall with a watchtower, a moat and a small outer defence to defend the Schwarzenberg lordly domain at its southernmost point.
Since a spring was found within the moat, the moat was called a “broad spring”, or breiten Brunnen in German, soon this description was taken up as the place’s name. Of special historic importance is the Breitenbrunn Papermill found in the town, from which, among others, Johann Sebastian Bach got his notepaper. In Catholic times, Breitenbrunn first belonged to the Parish of Schwarzenberg. A chapel consecrated to Saint Peter was built, making Breitenbrunn into a Schwarzenberg branch parish. After the Reformation, a dependent relationship was maintained for the time being. Now, Breitenbrunn was a daughter community of the newly established parish of Grünstädtel; the village at last got its ecclesiastical independence in 1559, in which same year St. Christopher’s Church was built. Chosen as the location was the village’s upper end to make the walk for churchgoers from the neighbouring, parochially united community of Rittersgrün somewhat easier in the winter months. Today, alongside the Evangelical Lutheran community of St. Christopher is an Evangelical Methodist community.
Data from 1999 on: Statistisches Landesamt Sachsen The community’s mayor Ralf Fischer, born in 1955, was elected in the latest mayoral contest on 10 June 2001 with 98.4% of all the votes. The other 1.6 % was shared by other candidates. Nattheim, Baden-Württemberg St. Christoph visitors‘ mine Silberwäsche Technical Museum in the constituent community of Antonsthal Christophoruskirche from 1559 Memorial to the Plague Minister Wolfgang Uhle at cemetery entrance Hunting lodge ruins “Himmelswiese” natural monument near the constituent community of Halbemeile Preißhausbuche, a famous beech tree Breitenbrunn is known for its Staatliche Studienakademie Breitenbrunn. Here 300 students are taught by the dual principle in the fields of tourism economics and welfare. Rabenberg Sport and Education Centre Church consecration festival in the upper village on the last weekend of August Sven Hannawald, ski jumper Wolfgang Uhle, known as the “Plague Minister” of Annaberg, was minister in Breitenbrunn from 1569 to 1594.
Christian Gottlob Wild and dialect poet, died here in 1839. Community’s webpage Visitors’ mine
Iron ores are rocks and minerals from which metallic iron can be economically extracted. The ores are rich in iron oxides and vary in colour from dark grey, bright yellow, or deep purple to rusty red; the iron is found in the form of magnetite, goethite, limonite or siderite. Ores containing high quantities of hematite or magnetite are known as "natural ore" or "direct shipping ore", meaning they can be fed directly into iron-making blast furnaces. Iron ore is the raw material used to make pig iron, one of the main raw materials to make steel—98% of the mined iron ore is used to make steel. Indeed, it has been argued that iron ore is "more integral to the global economy than any other commodity, except oil". Metallic iron is unknown on the surface of the Earth except as iron-nickel alloys from meteorites and rare forms of deep mantle xenoliths. Although iron is the fourth most abundant element in the Earth's crust, comprising about 5%, the vast majority is bound in silicate or more carbonate minerals.
The thermodynamic barriers to separating pure iron from these minerals are formidable and energy intensive, therefore all sources of iron used by human industry exploit comparatively rarer iron oxide minerals hematite. Prior to the industrial revolution, most iron was obtained from available goethite or bog ore, for example during the American Revolution and the Napoleonic Wars. Prehistoric societies used laterite as a source of iron ore. Much of the iron ore utilized by industrialized societies has been mined from predominantly hematite deposits with grades of around 70% Fe; these deposits are referred to as "direct shipping ores" or "natural ores". Increasing iron ore demand, coupled with the depletion of high-grade hematite ores in the United States, after World War II led to development of lower-grade iron ore sources, principally the utilization of magnetite and taconite. Iron-ore mining methods vary by the type of ore being mined. There are four main types of iron-ore deposits worked depending on the mineralogy and geology of the ore deposits.
These are magnetite, massive hematite and pisolitic ironstone deposits. Banded iron formations are sedimentary rocks containing more than 15% iron composed predominantly of thinly bedded iron minerals and silica. Banded iron formations occur in Precambrian rocks, are weakly to intensely metamorphosed. Banded iron formations may contain iron in carbonates or silicates, but in those mined as iron ores, oxides are the principal iron mineral. Banded iron formations are known as taconite within North America; the mining involves moving tremendous amounts of waste. The waste comes in two forms, non-ore bedrock in the mine, unwanted minerals which are an intrinsic part of the ore rock itself; the mullock is mined and piled in waste dumps, the gangue is separated during the beneficiation process and is removed as tailings. Taconite tailings are the mineral quartz, chemically inert; this material is stored in regulated water settling ponds. The key economic parameters for magnetite ore being economic are the crystallinity of the magnetite, the grade of the iron within the banded iron formation host rock, the contaminant elements which exist within the magnetite concentrate.
The size and strip ratio of most magnetite resources is irrelevant as a banded iron formation can be hundreds of meters thick, extend hundreds of kilometers along strike, can come to more than three billion or more tonnes of contained ore. The typical grade of iron at which a magnetite-bearing banded iron formation becomes economic is 25% iron, which can yield a 33% to 40% recovery of magnetite by weight, to produce a concentrate grading in excess of 64% iron by weight; the typical magnetite iron-ore concentrate has less than 0.1% phosphorus, 3–7% silica and less than 3% aluminium. Magnetite iron ore is mined in Minnesota and Michigan in the U. S. Eastern Canada and Northern Sweden. Magnetite bearing banded iron formation is mined extensively in Brazil, which exports significant quantities to Asia, there is a nascent and large magnetite iron-ore industry in Australia. Direct-shipping iron-ore deposits are exploited on all continents except Antarctica, with the largest intensity in South America and Asia.
Most large hematite iron-ore deposits are sourced from altered banded iron formations and igneous accumulations. DSO deposits are rarer than the magnetite-bearing BIF or other rocks which form its main source or protolith rock, but are cheaper to mine and process as they require less beneficiation due to the higher iron content. However, DSO ores can contain higher concentrations of penalty elements being higher in phosphorus, water content and aluminum. Export grade DSO ores are in the 62–64% Fe range. Granite and ultrapotassic igneous rocks segregate magnetite crystals and form masses of magnetite suitable for economic concentration. A few iron ore deposits, notably in Chile, are formed from volcanic flows containing significant accumulations of magnetite phenocrysts. Chilean magnetite iron ore deposits within the Atacama Desert have formed alluvial accumulations of magnetite in s
Placer mining is the mining of stream bed deposits for minerals. This may be done by various surface excavating equipment or tunnelling equipment. Placer mining is used for precious metal deposits and gemstones, both of which are found in alluvial deposits—deposits of sand and gravel in modern or ancient stream beds, or glacial deposits; the metal or gemstones, having been moved by stream flow from an original source such as a vein, are only a minuscule portion of the total deposit. Since gems and heavy metals like gold are denser than sand, they tend to accumulate at the base of placer deposits, it is important to note that placer deposits can be as young as a few years old, such as the Canadian Queen Charlotte beach gold placer deposits, or billions of years old like the Elliott Lake uranium paleoplacer within the Huronian Supergroup in Canada. The containing material in an alluvial placer mine may be too loose to safely mine by tunnelling, though it is possible where the ground is permanently frozen.
Where water under pressure is available, it may be used to mine and separate the precious material from the deposit, a method known as hydraulic mining, hydraulic sluicing or hydraulicking. The word placer derives from the Spanish placer, meaning shoal or alluvial/sand deposit, from Catalan placer, from plassa, from Medieval Latin placea the origin word for "place" and "plaza" in English; the word in Spanish is thus derived from placea and refers directly to an alluvial or glacial deposit of sand or gravel. Placers supplied most of the gold for a large part of the ancient world. Hydraulic mining methods such as hushing were used by the Romans across their empire, but in the gold fields of northern Spain after its conquest by Augustus in 25 BC. One of the largest sites was at Las Médulas, where seven 30 mile long aqueducts were used to work the alluvial gold deposits through the first century AD. In North America, placer mining was famous in the context of several gold rushes the California Gold Rush and the Colorado Gold Rush, the Fraser Canyon Gold Rush and the Klondike Gold Rush.
Placer mining continues in many areas of the world as a source of diamonds, industrial minerals and metals, platinum, of gold. An area well protected from the flow of water is a great location to find gold. Gold is dense and is found in a stream bed. Many different gold deposits are dealt with in different ways. Placer deposits attract many prospectors because their costs are low. There are many different places gold could be placed, such as a residual, a bench deposit. Residual deposits are more common where there has been weathering on rocks and where there hasn’t been water, they are deposits which have not been been moved. The residual lies at the site of the lode; this type of deposit undergoes rock weathering. Alluvial or eluvial deposits sometimes have the largest gold deposit and are common; this deposit is created when a force of nature moves or washes the gold away, but it doesn’t go into a stream bed. It contains pieces of ore. Alluvial deposits are the most common type of placer gold; this type of deposit occurs in valleys.
Bench deposits are created. Gold accumulations in an old stream bed that are high are called bench deposits, they can be found on higher slopes. Dry stream beds can be situated far from other water sources and can sometimes be found on mountain tops. Today, many miners focus their activities on bench deposits. A number of methods are used to mine placer gold and gems, both in terms of extracting the minerals from the ground, separating it from the non-gold or non-gems; the simplest technique to extract gold from placer ore is panning. This technique has been dated back to at least the Roman Empire. In panning, some mined ore is placed in a large metal or plastic pan, combined with a generous amount of water, agitated so that the gold particles, being of higher density than the other material, settle to the bottom of the pan; the lighter gangue material such as sand and gravel are washed over the side of the pan, leaving the gold behind. Once a placer deposit is located by gold panning, the miner shifts to equipment that can treat volumes of sand and gravel more and efficiently.
Gold panning was used on its own during the California gold rush, however it is now used for profit since an expert gold prospector can only process one cubic yard of material for every 10 hours of work. A rocker box is capable of greater volume than a gold pan, however its production is still limited when compared to other methods of placer mining, it is only capable of processing about 4 yards of gravel a day. It is more portable and requires less infrastructure than a sluice box, being fed not by a sluice but by hand; the box sits on rockers, which when rocked separates out the gold, the practice was referred to as "rocking the golden baby". A typical rocker box is 42 inches long, 16 inches wide and 12 inches long with a removable tray towards the top, where gold is placed; the rocker was used throughout North America during the early gold rush, but its popularity diminished as other meth
Vehicle registration plate
A vehicle registration plate known as a number plate or a license plate, is a metal or plastic plate attached to a motor vehicle or trailer for official identification purposes. All countries require registration plates for road vehicles such as cars and motorcycles. Whether they are required for other vehicles, such as bicycles, boats, or tractors, may vary by jurisdiction; the registration identifier is a numeric or alphanumeric ID that uniquely identifies the vehicle owner within the issuing region's vehicle register. In some countries, the identifier is unique within the entire country, while in others it is unique within a state or province. Whether the identifier is associated with a vehicle or a person varies by issuing agency. There are electronic license plates. Most governments require a registration plate to be attached to both the front and rear of a vehicle, although certain jurisdictions or vehicle types, such as motorboats, require only one plate, attached to the rear of the vehicle.
National databases relate this number to other information describing the vehicle, such as the make, colour, year of manufacture, engine size, type of fuel used, mileage recorded, vehicle identification number, the name and address of the vehicle's registered owner or keeper. In the vast majority of jurisdictions, the government holds a monopoly on the manufacturing of vehicle registration plates for that jurisdiction. Either a government agency or a private company with express contractual authorization from the government makes plates as needed, which are mailed to, delivered to, or picked up by the vehicle owners. Thus, it is illegal for private citizens to make and affix their own plates, because such unauthorized private manufacturing is equivalent to forging an official document. Alternatively, the government will assign plate numbers, it is the vehicle owner's responsibility to find an approved private supplier to make a plate with that number. In some jurisdictions, plates will be permanently assigned to that particular vehicle for its lifetime.
If the vehicle is either destroyed or exported to a different country, the plate number is retired or reissued. China requires the re-registration of any vehicle that crosses its borders from another country, such as for overland tourist visits, regardless of the length of time it is due to remain there. Other jurisdictions follow a "plate-to-owner" policy, meaning that when a vehicle is sold the seller removes the current plate from the vehicle. Buyers must either obtain new plates or attach plates they hold, as well as register their vehicles under the buyer's name and plate number. A person who sells a car and purchases a new one can apply to have the old plates put onto the new car. One who sells a car and does not buy a new one may, depending on the local laws involved, have to turn the old plates in or destroy them, or may be permitted to keep them; some jurisdictions permit the registration of the vehicle with "personal" plates. In some jurisdictions, plates require periodic replacement associated with a design change of the plate itself.
Vehicle owners may or may not have the option to keep their original plate number, may have to pay a fee to exercise this option. Alternately, or additionally, vehicle owners have to replace a small decal on the plate or use a decal on the windshield to indicate the expiration date of the vehicle registration, periodic safety and/or emissions inspections or vehicle taxation. Other jurisdictions have replaced the decal requirement through the use of computerization: a central database maintains records of which plate numbers are associated with expired registrations, communicating with automated number plate readers to enable law-enforcement to identify expired registrations in the field. Plates are fixed directly to a vehicle or to a plate frame, fixed to the vehicle. Sometimes, the plate frames contain advertisements inserted by the vehicle service centre or the dealership from which the vehicle was purchased. Vehicle owners can purchase customized frames to replace the original frames. In some jurisdictions registration plate frames have design restrictions.
For example, many states, like Texas, allow plate frames but prohibit plate frames from covering the name of the state, district, Native American tribe or country that issued of license plate. Plates are designed to conform to standards with regard to being read by eye in day or at night, or by electronic equipment; some drivers purchase clear, smoke-colored or tinted covers that go over the registration plate to prevent electronic equipment from scanning the registration plate. Legality of these covers varies; some cameras incorporate filter systems that make such avoidance attempts unworkable with infra-red filters. Vehicles pulling trailers, such as caravans and semi-trailer trucks, are required to display a third registration plate on the rear of the trailer. An engineering study by the University of Illinois published in 1960 recommended that the state of Illinois adopt a numbering system and plate design "composed of combinations of characters which can be perceived and are legible at a distance of 125 feet under daylight conditions, are adapted to filing and administrative procedures".
It recommended that a standard plate size of 6 inches by 14 inches be adopte