The Canterbury Tales (Middle English: Tales of Caunterbury) is a collection of twenty-four stories that runs to over 17,000 lines written in Middle English by Geoffrey Chaucer between 1387 and 1400. It is widely regarded as Chaucer's magnum opus. The tales (mostly written in verse, although some are in prose) are presented as part of a story-telling contest by a group of pilgrims as they travel together from London to Canterbury to visit the shrine of Saint Thomas Becket at Canterbury Cathedral. The prize for this contest is a free meal at the Tabard Inn at Southwark on their return.

It has been suggested that the greatest contribution of The Canterbury Tales to English literature was the popularisation of the English vernacular in mainstream literature, as opposed to French, Italian or Latin. English had, however, been used as a literary language centuries before Chaucer's time, and several of Chaucer's contemporariesJohn Gower, William Langland, the Pearl Poet, and Julian of Norwichalso wrote major literary works in English. It is unclear to what extent Chaucer was seminal in this evolution of literary preference.

The Canterbury Tales is generally thought to have been incomplete at the end of Chaucer's life. In the General Prologue, some 30 pilgrims are introduced. According to the Prologue, Chaucer's intention was to write four stories from the perspective of each pilgrim, two each on the way to and from their ultimate destination, St. Thomas Becket's shrine (making for a total of about 120 stories). Although perhaps incomplete, The Canterbury Tales is revered as one of the most important works in English literature.

Geoffrey Chaucer (; c. 1340s – 25 October 1400) was an English poet, author, and civil servant best known for The Canterbury Tales. He has been called the "father of English literature", or, alternatively, the "father of English poetry". He was the first writer to be buried in what has since come to be called Poets' Corner, in Westminster Abbey. Chaucer also gained fame as a philosopher and astronomer, composing the scientific A Treatise on the Astrolabe for his 10-year-old son Lewis. He maintained a career in the civil service as a bureaucrat, courtier, diplomat, and member of parliament.

Among Chaucer's many other works are The Book of the Duchess, The House of Fame, The Legend of Good Women, and Troilus and Criseyde. He is seen as crucial in legitimising the literary use of Middle English when the dominant literary languages in England were still Anglo-Norman French and Latin. His contemporary Thomas Hoccleve hailed Chaucer as "the firste fyndere of our fair langage". Almost two thousand English words are first attested to in Chaucerian manuscripts.