An encyclopedia or encyclopaedia is a reference work or compendium providing summaries of knowledge either from all branches or from a particular field or discipline. Encyclopedias are divided into articles or entries that are arranged alphabetically by article name and sometimes by thematic categories. Encyclopedia entries are more detailed than those in most dictionaries. Speaking, unlike dictionary entries—which focus on linguistic information about words, such as their etymology, pronunciation and grammatical forms—encyclopedia articles focus on factual information concerning the subject named in the article's title. Encyclopedias have existed for around 2,000 years and have evolved during that time as regards to language, intent, cultural perspective, authorship and the technologies available for their production and distribution; as a valued source of reliable information compiled by experts, printed versions found a prominent place in libraries and other educational institutions. The appearance of digital and open-source versions in the 21st century has vastly expanded the accessibility, authorship and variety of encyclopedia entries.

The word encyclopedia comes from the Koine Greek ἐγκύκλιος παιδεία, transliterated enkyklios paedia, meaning "general education" from enkyklios, meaning "circular, required general" and paedia, meaning "education, rearing of a child". However, the two separate words were reduced to a single word due to a scribal error by copyists of a Latin manuscript edition of Quintillian in 1470; the copyists took this phrase to be a single Greek word, with the same meaning, this spurious Greek word became the New Latin word "encyclopaedia", which in turn came into English. Because of this compounded word, fifteenth century readers and since have and incorrectly, thought that the Roman authors Quintillian and Pliny described an ancient genre. In the sixteenth century there was a level of ambiguity as to; as several titles illustrate, there was not a settled notion about its spelling nor its status as a noun. For example: Jacobus Philomusus's Margarita philosophica encyclopaediam exhibens. There have been two examples of the oldest vernacular use of the compounded word.

In 1490, Franciscus Puccius wrote a letter to Politianus thanking him for his Miscellanea, calling it an encyclopedia. More François Rabelais is cited for his use of the term in Pantagruel. Several encyclopedias have names that include the suffix -pedia, to mark the text as belonging to the genre of encyclopedias. An example is Banglapedia. Today in English, the word is most spelled encyclopedia, though encyclopaedia is used in Britain; the modern encyclopedia was developed from the dictionary in the 18th century. Both encyclopedias and dictionaries have been researched and written by well-educated, well-informed content experts, but they are different in structure. A dictionary is a linguistic work which focuses on alphabetical listing of words and their definitions. Synonymous words and those related by the subject matter are to be found scattered around the dictionary, giving no obvious place for in-depth treatment. Thus, a dictionary provides limited information, analysis or background for the word defined.

While it may offer a definition, it may leave the reader lacking in understanding the meaning, significance or limitations of a term, how the term relates to a broader field of knowledge. An encyclopedia is, not written in order to convince, although one of its goals is indeed to convince its reader of its own veracity. To address those needs, an encyclopedia article is not limited to simple definitions, is not limited to defining an individual word, but provides a more extensive meaning for a subject or discipline. In addition to defining and listing synonymous terms for the topic, the article is able to treat the topic's more extensive meaning in more depth and convey the most relevant accumulated knowledge on that subject. An encyclopedia article often includes many maps and illustrations, as well as bibliography and statistics. Four major elements define an encyclopedia: its subject matter, its scope, its method of organization, its method of production: Encyclopedias can be general, containing articles on topics in every field.

General encyclopedias may contain guides on how to do a variety of things, as well as embedded dictionaries and gazetteers. There are encyclopedias that cover a wide variety of topics from a particular cultural, ethnic, or national perspective, such as the Great Soviet Encyclopedia or Encyclopaedia Judai

San Vittore is a prison in the city center of Milan, Italy. Its construction started in 1872 and opened on 7 July 1879; the prison has place for 600 inmates, but it had 1036 prisoners in 2017. The construction of the new prison was decided after the Italian unification, together with other infrastructure improvement works in Milan in the period between the unification and the city's first town plan of 1889; until prisoners were detained in several other structures not designed as prisons, among them the former Sant'Antonio Abate convent, in the Courthouse and in the former San Vittore convent. For the construction of the new structure the government acquired terrains in the outskirts of the city, in a sparsely developed area at that time; the building, designed by the engineer Francesco Lucca, takes inspiration from the 18th century Panopticon, with 6 wings with three floors each. The perimeter walls were built in medieval style, but they have all been rebuilt with modern standards for security reasons.

During Fascism occupation the San Vittore Prison was used as an house for every enemy. Since Germans took over the power in Italy, in 1943, a lot of changes happened in the prison, until the big riots happened in the April of 1946. During the German occupation in World War II the prison was subject to German jurisdiction, with the SS in control of one of the wings; the prison gained notoriety during the war through the inhumane treatment of inmates by the SS guards and the torture carried out there. On 10 August 1944 15 captured partisans held at the prison, hand picked by Theo Saevecke, head of the Gestapo in Milan, were publicly executed at Piazzale Loreto and left on display, as a reprisal for a partisan attack on a German military convoy; the prisons served as a way station for Jews arrested in northern Italy, which would be brought to San Vittore Prison and, from there, to Milano Centrale railway station, from where they would be loaded into freight cars on a secret track underneath the station.

Mike Bongiorno, television host. Detained for 7 months in 1943 before being transferred to Mauthausen concentration camp. Indro Montanelli and historian, shared prison cell with Bongiorno. Gaetano Bresci, detained from 29 July to 5 November 1900. Renato Vallanzasca, Italian criminal. Salvatore Riina, Italian criminal, former chief of the Sicilian Mafia. Fabrizio Corona, television personality. Patrizia Reggiani, ex-wife of Maurizio Gucci. Dorothy Gibson, American actress and Titanic survivor. Ebrei genovesi ricordano Luigi Borgomaneri, Hitler a Milano: crimini di Theodor Saevecke capo della Gestapo, Datanews, 1997. E. Grottanelli, L'amministrazione comunale di Milano e la costruzione del carcere di San Vittore, in "Storia in Lombardia" quadrimestrale dell'Istituto lombardo per la storia del movimento di liberazione in Italia, Franco Angeli Editore, anno IV, n. 2, 1985. Antonio Quatela, "Sei petali di sbarre e cemento", Mursia Editore, Milano, 2013

The Battle of Diwaniya took place in Al Diwaniyah, 180 kilometers south of Baghdad, on 28 August 2006 between the Mahdi Army and the Iraqi Army. The fighting erupted after coalition troops arrested a Sadr militia leader; the militia engaged in heavy street fighting with Iraqi soldiers. Militia fighters were entrenched in residential areas during the fighting; the Iraqi Army claims that most of its casualties occurred when Mahdi militiamen captured and executed a group of soldiers who had run out of ammunition. By next morning a ceasefire was in place with 23 Iraqi soldiers, 20 militiamen and 7 civilians killed. About a month and a half on 9 October 2006 another battle broke out in the city, this time between the militia and the U. S. Army. Thirty militiamen were killed and a U. S. military tank was damaged. Battle of Amarah Operation Black Eagle Operation Lion's Leap