English is known as a world language, regularly used by many nations whose English is not their first language. Like other languages, English has changed greatly. The history of the English language can be divided into threee main periods: Old English, Middle English and Modern English. The English language started with the invasion of Britain by three Germanic tribes during the 5th century AD, and they contributed greatly to the formation of the English language. During the medieval and early modern periods, the influence of English spread throughout the British Isles, and from the Early 17th century its influence began to be felt throughout the world.The processes of European exploration and colonization for several centuries led to significant change in English. Today, American English is particularly influential, due to the popularity of American cinema, television, music, trade and technology, including the Internet.