The Pali Canon
The Tipitaka (Pali ti, "three," + pitaka, "baskets"), or Pali Canon, is the collection of primary Pali language texts which form the doctrinal foundation of Theravada Buddhism. Together with the ancient commentaries, they constitute the complete body of classical Theravada texts.
The Pali Canon is a vast body of literature: in English translation the texts add up to several thousand printed pages. Most (but not all) of the Canon has already been published in English over the years. Although only a small fraction of these texts are available on this website, this collection can be a good place to start.
The three divisions of the Tipitaka are:
The collection of discourses, attributed to the Buddha and a few of his closest disciples, containing all the central teachings of Theravada Buddhism. (Over seven hundred sutta translations are available here.)
The collection of texts concerning the rules of conduct governing the daily affairs within the Sangha -- the community of bhikkhus (ordained monks) and bhikkhunis(ordained nuns). Far more than merely a list of rules, the Vinaya Pitaka also includes the stories behind the origin of each rule, providing a detailed account of the Buddha's solution to the question of how to maintain communal harmony within a large and diverse spiritual community.
The collection of texts in which the underlying doctrinal principles presented in the Sutta Pitaka are reworked and reorganized into a systematic framework that can be applied to an investigation into the nature of mind and matter.