Encyclopedia

An encyclopedia (American English) or encyclopædia (British English) is a reference work or compendium providing summaries of knowledge either general or special to a particular field or discipline.[1][2] Encyclopedias are divided into articles or entries that are arranged alphabetically by article name[3] or by thematic categories, or else are hyperlinked and searchable.[4] Encyclopedia entries are longer and more detailed than those in most dictionaries.[3][5] Generally speaking, encyclopedia articles focus on factual information concerning the subject named in the article's title;[5] this is unlike dictionary entries, which focus on linguistic information about words, such as their etymology, meaning, pronunciation, use, and grammatical forms.[5][6][7][8][9]

Encyclopedias have existed for around 2,000 years and have evolved considerably during that time as regards language (written in a major international or a vernacular language), size (few or many volumes), intent (presentation of a global or a limited range of knowledge), cultural perspective (authoritative, ideological, didactic, utilitarian), authorship (qualifications, style), readership (education level, background, interests, capabilities), and the technologies available for their production and distribution (hand-written manuscripts, small or large print runs, Internet). As a valued source of reliable information compiled by experts, printed versions found a prominent place in libraries, schools and other educational institutions.

The appearance of digital and open-source versions in the 21st century, such as Wikipedia, has vastly expanded the accessibility, authorship, readership, and variety of encyclopedia entries.[10]