Wikipedia (/ˌwɪkɪˈpdiə/ (About this soundlisten)/ˌwɪkiˈpdiə/ (About this soundlisten) WIK-ih-PEE-dee-ə) is a multilingual online encyclopedia with exclusively free content and no ads (though donations are accepted), based on open collaboration through a model of content editing using web-based applications such as web browsers, called wiki. It is the largest and most popular general reference work on the World Wide Web,[3][4][5] and is one of the most popular websites by Alexa rank as of April 2019.[6] It is owned and supported by the Wikimedia Foundation, a non-profit organization that operates on money it receives from donors to remain ad-free.[7][8][9][10]

Wikipedia was launched on January 15, 2001, by Jimmy Wales and Larry Sanger.[11] Sanger coined its name,[12][13] as a portmanteau of wiki (the Hawai’ian word for “quick”[14]) and “encyclopedia“. Initially an English-language encyclopedia, versions in other languages were quickly developed. With 5,861,248 articles,[notes 3] the English Wikipedia is the largest of the more than 290 Wikipedia encyclopedias. Overall, Wikipedia comprises more than 40 million articles in 301 different languages[15] and by February 2014 it had reached 18 billion page views and nearly 500 million unique visitors per month.[16]

In 2005, Nature published a peer review comparing 42 hard science articles from Encyclopædia Britannica and Wikipedia and found that Wikipedia’s level of accuracy approached that of Britannica,[17] although critics suggested that it might not have fared so well in a similar study of a random sampling of all articles or one focused on social science or contentious social issues.[18][19] The following year, Time magazine stated that the open-door policy of allowing anyone to edit had made Wikipedia the biggest and possibly the best encyclopedia in the world, and was a testament to the vision of Jimmy Wales.[20]

Wikipedia has been criticized for exhibiting systemic bias, for presenting a mixture of “truths, half truths, and some falsehoods”,[21] and for being subject to manipulation and spin in controversial topics.[22] But by 2017, Facebook announced that it would help readers detect fake news by suggesting links to related Wikipedia articles. YouTube announced a similar plan in 2018.[23]


The United States of America (USA), commonly referred to as the United States (U.S.), America, and sometimes the States, is a federal republic[17][18] consisting of 50 statesand a federal district. The 48 contiguous states and Washington, D.C., are in central North America between Canada and Mexico. The state of Alaska is located in the northwestern part of North America and the state of Hawaii is an archipelago in the mid-Pacific. The country also has five populated and nine unpopulated territories in the Pacific and the Caribbean. At 3.80 million square miles (9.85 million km2)[4] and with around 318 million people, the United States is the world’s fourth-largest country by total area and third-largest by population. It is one of the world’s most ethnically diverse and multicultural nations, the product of large-scale immigration from many countries.[19]The geography and climate of the United States is also extremely diverse, and it is home to a wide variety of wildlife.[20]

The United States is a developed country and has the world’s largest national economy.[6] The economy is fueled by an abundance of natural resources and high worker productivity.[29] While the U.S. economy is considered post-industrial, it continues to be one of the world’s largest manufacturers.[30] The country accounts for 37% of global military spending,[31] being the world’s foremost economic and military power, a prominent political and cultural force, and a leader in scientific research and technological innovations.[32]