Middle English is a version of the English language used in medieval times, roughly between the Norman Conquest of 1066 and the late 15th Century A.D. Many famous works were written in Middle English, such as The Canterbury Tales, Le Morte d'Arthur, Piers Plowman, and Sir Gawain and the Green Knight.
The best-known example of Middle English is the opening of Geoffrey Chaucer's The Canterbury Tales:
Whan that Aprill, with his shoures soote
The droghte of March hath perced to the roote
And bathed every veyne in swich licour,
Of which vertu engendred is the flour;
Whan Zephirus eek with his sweete breeth
Inspired hath in every holt and heeth
The tendre croppes, and the yonge sonne
Hath in the Ram his halfe cours yronne,
And smale foweles maken melodye,
That slepen al the nyght with open eye-
(So priketh hem Nature in hir corages);
Thanne longen folk to goon on pilgrimages
And palmeres for to seken straunge strondes
To ferne halwes, kowthe in sondry londes;
And specially from every shires ende
Of Engelond, to Caunterbury they wende,
The hooly blisful martir for to seke
That hem hath holpen, whan that they were seeke.
Rough prose translation: When April's sweet showers have pierced the droughts of March to the root and bathed every vein in the liquor by which force flowers are brought forth; also, when Zephirus [the Spring wind] with his sweet breath has inspired the tender crops in every holt [small woods] and heath, and the young sun has run half its course in the Ram [the constellation Aries], and small fowls, which sleep all night with open eyes, make melody (as Nature spurs them in their hearts); then folk long to go on pilgrimages and palmers [pilgrims who have visited the Holy Land] to seek foreign shores for distant shrines, well-known in many lands; and especially, from the ends of every shire [county] of England they wend their way to Canterbury to seek the holy blessed martyr [Saint Thomas Becket] who helped them when they were sick.