W3

W3 or W-3 may refer to:


 * W3 (tram), a class of electric trams built by the Melbourne & Metropolitan Tramways Board
 * W3, a postcode district in the W postcode area
 * Apple W3, a wireless chip used in the Apple Watch Series 4.
 * PZL W-3 Sokół, a Polish helicopter
 * The Amazing 3, a manga and anime series, known in Japan as Wonder 3
 * Arik Air, which has IATA code W3
 * The fourth step of the W0-W6 scale for the classification of meteorites by weathering
 * The U.S. Internal Revenue Service form W-3, a transmittal form for Form W-2 information
 * Webster's Third New International Dictionary, the 1961 edition of Webster's Dictionary
 * The World Wide Web, abbreviated 'W3' on the earliest web pages
 * World Wide Web Consortium, international standards organization for the World Wide Web (abbreviated WWW or W3)
 * Windows 3.0, a Microsoft operating system

Video games

 * Warcraft III: Reign of Chaos, the third game in the Warcraft series.
 * Worms & Reinforcements United, a game bundle composing the first Worms game and the Worms Reinforcements expansion pack