Geoffrey Chaucer was an English poet and author who lived in the 14th century. He is best known for his work "The Canterbury Tales," a collection of stories written in Middle English that provides a vivid picture of medieval life. Chaucer is often referred to as the "Father of English literature" due to his significant contributions to the development of the English language and his influence on later generations of writers. His writing style and use of vernacular language helped to popularize English as a literary language, and his works continue to be studied and celebrated for their insight into the social and cultural aspects of his time.