The history of the English language in fact started with the arrival of three Germanic tribes who conquered Britain during the 5th century AD. These ethnic groups, the Angles, the Saxons and the Jutes, crossed the North Sea from what today is Denmark and northern Germany. At that time the inhabitants of Britain spoke a Celtic language. Celts are a member of an ancient group of people who lived in parts of Western Europe. But most of the Celtic speakers were moved towards west and north by the invaders - mainly into what is now Wales, Scotland and Ireland. The Angles came from Englaland and their language was called Englisc – from which the words England and English are derived. (Also called Anglo-Saxon is an early form of the English that was spoken and written in parts of what are now England and south-eastern Scotland between the mid-5th century and the mid-12th century).
Historically English originated from several dialects, now collectively termed Old English. Old English developed into Middle English, words heavily borrowing from the Norman (Anglo-French) vocabulary and spelling gatherings. A significant number of English words, especially technical words, have been constructed based on roots from Latin and ancient Greek as well.
As a result of the military, economic, scientific, political, and cultural influence of the British Empire during the 18th, 19th, and early 20th centuries and of the United States since the mid 20th century it has become the lingua franca (language that people use to communicate when they have different first languages) in many parts of the world.
It is used extensively as a second language and as an official language in Commonwealth countries (an organization of countries that used to be under the political control of the United Kingdom) and many international organizations. Also English is the official language of Olympics.