The Angelo-Saxons

When? The Angelo-Saxons invaded Britain in the fifth and sixth centuries.

Why?  They gave the English language the first words.

How?:  Many of them was farmers so they added many farming words to the English Vocabulary.

Scandinavian settlement

When? The Scandinavians started to migrate to England in the middle of the 9th century.

Why? They gave many words to the English language.

How? Scandinavia and England was very close and it was such a great influence that they almost had the same languages.

1066 and after

When? The event happened in 1066 and some years after.

Why? After William the conqueror defeated Harold Godwinson at the battle of Hastings, English underwent enormous changes

How? The vocabulary became much bigger because of the French loan words.

Standardization

When? In the late medieval and early modern periods.

Why? Spelling became standardized.

How? Words became more modern and  the pronunciation changed.

Colonization and Globalization

When? From the 1600 and onward.

Why? English became a world language.

How? They got many new loan words and and many varieties.