The historical development of a language is a continuous uninterrupted process without sudden breaks or rapid transformations. Therefore any periodisation imposed on language history by linguists, with precise dates, might appear artificial. 

The commonly accepted, traditional periodisation devides English history into three periods:

OLD ENGLISH 

MIDDLE ENGLISH 

NEW ENGLISH 

OLD ENGLISH begins with Germanic settlement of Britain (5th century) or with the beginning of writing (7th century) and ends with the Norman Conquest (1066);

MIDDLE ENGLISH begins with the Norman Conquest and ends on the introduction of printing (1475)

MODERN OR NEW ENGLISH PERIOD

begins with the introduction of printing and lasts to the present day.