Welcome to Wikipedia

,

the free encyclopedia that anyone can edit.

From today's featured article

Modus ponens, one of the valid forms of inference studied in logic

Logic is the study of correct reasoning. Formal logic aims to determine the correctness of arguments based on their structure alone and often uses a formal language to analyze them. Informal logic examines arguments expressed in natural language and also takes their content and context into account. Logic distinguishes between deductive, inductive, and abductive arguments. Deductive arguments have the strongest form of support: if their premises are true then their conclusion must also be true, such as in the argument "today is Sunday; if today is Sunday then I do not have to work today; therefore I do not have to work today". Inductive arguments are generalizations, like inferring that all ravens are black based on many individual observations. Abductive arguments are inferences to the best explanation, for instance, when a doctor concludes that a patient has a certain disease that explains the symptoms they suffer. Arguments that fall short of the standards of reasoning embody fallacies. (Full article...)

Recently featured:

Did you know ...

A bacterium that thrives in the deep ocean

... that life exists in every part of the biosphere, from the deepest parts of the ocean (bacterium pictured) to altitudes of up to 64 km (40 miles) in the atmosphere?
... that Spyridon Marinatos discovered the battlefield of Thermopylae in 1939?
... that in 1944, the Tuvan-language journal Lenin–Stalinnьꞑ tugunuꞑ adaa-pile switched from the Latin script to the Cyrillic script?
... that railroad engineer Jules Hanscotte developed a system for the safe braking of heavy trains on steep gradients, but its only significant use was on tourist tramways?
... that William Sharpington and his workshop created what was described as "some of the most distinguished" public lettering in post-war England?
... that before a separate party was created for Pakistan, the All India Scheduled Castes Federation simultaneously held the posts of Minister of Law in both Pakistan and India?
... that the owner of the Washington Wolfpack said that he initially only wanted to try out some players from his semi-professional team, but they gave him ownership instead?
... that one legend claimed that Hö'elün conceived the boy who would become Genghis Khan when she was impregnated by a ray of light?

In the news

Sam Bankman-Fried

An earthquake strikes Karnali Province, Nepal, leaving more than 150 people dead.
American entrepreneur Sam Bankman-Fried (pictured) is convicted on charges of fraud and money laundering over his role in the bankruptcy of cryptocurrency exchange FTX.
NASA's Lucy space probe flies by the asteroid Dinkinesh, the first target of the mission.
In baseball, the Texas Rangers defeat the Arizona Diamondbacks to win the World Series.

On this day

November 5: Guy Fawkes Night in Great Britain and some Commonwealth countries (1605)

Aline Chrétien

1138 – Lý Anh Tông was enthroned as the emperor of Đại Việt at the age of two, beginning a 37-year reign.
1943 – World War II: An unknown aircraft dropped four bombs on Vatican City, which maintained neutrality during the war.
1995 – Aline Chrétien (pictured) thwarted André Dallaire's attempt to assassinate her husband, Canadian prime minister Jean Chrétien, by locking the bedroom door in 24 Sussex Drive, their official residence in Ottawa.
2003 – American serial killer Gary Ridgway pleaded guilty to 48 counts of first-degree murder.
2013 – The Indian Space Research Organisation launched the Mars Orbiter Mission, India's first interplanetary probe.

Louis Bertrand Castel (b. 1688)
Edwin Flack (b. 1873)
James Robert Baker (d. 1997)
Habibollah Asgaroladi (d. 2013)

More anniversaries:

Today's featured picture

Pontia edusa, also known as the eastern Bath white, is a butterfly in the family Pieridae. It is found from southeastern Europe (southern France, Italy, Corsica, Sardinia) up to central Europe and the Middle East in Iran and Iraq. It is a migrant which can also be encountered in Belgium, Holland, northern Germany and Poland, in the Baltic states and in southern Sweden and Norway. It resides in open grassy or flowery areas, in stony or rocky places and in roadsides, especially where the host plants grow, at an altitude of up to 2,300 metres (7,500 ft). This P. edusa butterfly was photographed near the Elbe in Rühstädt, Germany.

Photograph credit: Sven Damerow

Recently featured:

Other areas of Wikipedia

Community portal – The central hub for editors, with resources, links, tasks, and announcements.
Village pump – Forum for discussions about Wikipedia itself, including policies and technical issues.
Site news – Sources of news about Wikipedia and the broader Wikimedia movement.
Teahouse – Ask basic questions about using or editing Wikipedia.
Help desk – Ask questions about using or editing Wikipedia.
Reference desk – Ask research questions about encyclopedic topics.
Content portals – A unique way to navigate the encyclopedia.

Wikipedia's sister projects

Wikipedia is written by volunteer editors and hosted by the Wikimedia Foundation, a non-profit organization that also hosts a range of other volunteer projects: