The teachings of the Buddha are preserved in the Pāli Canon, an extensive, detailed, systematic, and analytical record. Just as Sanskrit is the canonical language of Hinduism and Latin the canonical language of Catholicism, Pāli is the classical language in which the teachings of the Buddha have been preserved.
The Pāli Canon, or Tipiṭaka (ti-three + piṭaka-basket), consists of the Vinaya Piṭaka (discipline for the monks), the Sutta Piṭaka (discourses by the Buddha) and the Abhidhamma Piṭaka (higher teaching). Studying these texts is called pariyatti, applying the teaching to practice is called paṭipatti.
The Pali sources are the Tipiṭaka (the Pāli Canon), the commentaries (Aṭṭhakatha), and the sub-commentaries (Tika). More information on the Tipiṭaka.