Romeo and Juliet by William Shakespeare is written in English. Shakespeare's works, including Romeo and Juliet, are considered among the best and most beautiful poetry in the English language.
The English language is normally divided into Old English, Middle English, and Modern English, according to the following criteria:
Old English or Anglo-Saxon: (ca. 450 AD to 1066 AD) was a west Germanic language spoken in England. The best known work in it is the epic Beowulf. It differs greatly from modern English in both syntax and vocabulary.
Middle English (1066 to 1480): Middle English begins with the Norman Conquest which brought many French loan words into the English language. This also marks the beginning of the Great Vowel Shift and other changes in pronunciation, simplifications of grammar, and shifts in spelling. The best known poet from the period is Chaucer.
Early Modern English (c. 1480 to 1650): Shakespeare is an example of early modern English. Although spelling was not fully standardized until the eighteenth century, Shakespeare's English is quite close to twenty-first century English in vocabulary and grammar. Although 21st century readers may occasionally need to consult a dictionary, and read carefully, most native and near-native English speakers should be able to read Shakespeare's English.
Modern English: The modern English period begins in 1650; by this date, vocabulary, spelling, and grammar begun to be regularized and the Great Vowel shift completed, making pronunciation fairly close to our current version.
Modern English (1650 through present)