Shakespeare used different writing styles for the social status of the character. For example; The nobility tend to speak in "blank verse," which is essentially unrhymed poetry. The commoners tend to speak just like we do, in regular old prose.
The Earl of Surrey introduced blank verse in English literature in 1540. Milton, Shakespeare, Marlowe, John Donne, John Keats and many other poets and dramatists have used this device in their works. Have a look at some examples of blank verse.
The English language owes a great debt to Shakespeare. He invented over 1700 of our common words by changing nouns into verbs, changing verbs into adjectives, connecting words never before used together, adding prefixes and suffixes, and devising words wholly original.