English is one of the working languages of the United Nations and the de facto language of international communication. English belongs to the West Germanic branch of the Germanic family of Indo-European language family, which spread to all parts of the world through active English colonization.

Due to contact with many national languages in history, vocabulary has changed from unitary to pluralistic, grammar has changed from "more inflections" to "less inflections", and pronunciation has changed regularly. According to the number of native speakers, English may be the third largest language in the world, but it is the most extensive second language in the world.

More than 60% of the letters in the world are written in English. The leading position of Britain and America in culture, economy, military, politics and science in the past two centuries has made English a quasi-international language.