Compared with other figures of the time, Geoffrey Chaucer's early life was well documented. This leads historians to believe that his family was both rich and well-connected. He was born in London around 1343, and as teenager served as a page and then in the 100 Years War. Upon returning to England, he married, possibly attended university, and went into the service of King Edward III, followed by Richard II.
It's thought that this was around the time that Chaucer gained notoriety as a writer. There's a record of Edward III granting Chaucer 1 jug of wine a day for the rest of his life for an unspecified task (which was converted to a daily sum in the reign of Richard II. As Chaucer traveled Europe as diplomat of the English court, his works are sometimes grouped into the region that influenced the bodies of work in terms of content and style:
Chaucer died of unknown causes in 1400, and while there are rumors that he was murdered, there's no real evidence to support that idea. His remains were the first to be re-interred in 1556 in what is now known as the "Poet's Corner."
The above is an example of Middle English, the style Chaucer used to compose Canterbury Tales, spelled phonetically. It's significant because, up to this point, English wasn't recognized as a suitable "tongue" for literature--great works were written in Italian, French or Latin.
Chaucer developed a vision of English poetry that would be accessible to all, not just those who could read and write foreign languages. On top of composing his works in English, Chaucer used the vernacular, or the English that spoken in and around London at the time--which has a resemblence to the English spoken in the 20th century. Compare that with Old English (the language of Beowulf), which can only be read via modern translation or by students of Old English.
It's important to read Canterbury Tales the way that it was written, not only becuase it's similar to today's version, but the beauty of the language, rhymes, humor, and the way it sounds--it would all be lost if it were translated.
The easiest way for a beginner to approach Middle English to read it out loud, carefully and slowly, since most of the words are spelled phonetically and it's easier to understand them spoken out loud versus in your mind. Depending on the version you're using, most contain a guide for how to sound out Middle English words as well as supplementary explanations throughout the text for what's going on.
The slide show gives short descriptions of each portion of Canterbury Tales.
Canterbury Tales is a collection of stories told by people on a pilgramage to Canterbury, specifically the shrine of Sir Thomas Becket. The stories and characters depict a caricature of English society and the Church at the time, usually critical and ironic, sometimes silly and comical.
Though Chaucer wrote several other collections in his lifetime, Canterbury Tales is considered his best and most renowned work for reasons already touched on:
Canterbury Tales was never finished. Several medieval authors added to the tales, but it's the core of Chaucer's work that survives and is revered today.