Buddhism is a religion based on the teachings of the Buddha. For this reason, the words expounded by Shakyamuni Buddha have absolute authority and the sutras are collections of his sermons. "Sutra" is a Sanskrit word that referred in Brahmanism to those holy scriptures in which all sorts of teachings and regulations were recorded. This word is not unique to Buddhism and originally meant a “line” or “string.”
Following the death of Shakyamuni Buddha, his teachings were passed down from person to person by his disciples. However his disciples, concerned about the gradual changes in the contents of the teaching, gathered in a council to collect, organize, and correct the oral record of the Buddha's teachings.
At this council, the Buddha's successor (Mahakashapa) took a leading role. The sutras were corrected according to the memory of Ananda, who had the best memory of the Buddha's great disciples, and the precepts corrected according to the memory of Upali, who was said to have been preeminent in the practice of the precepts among the Buddha's great disciples. These records were put together by a large number of the Buddha's disciples who were, in this way, able to check and verify what had been heard as the Buddha's teaching and give their consent to it.
Finally, studies and commentaries on the sutras and precepts were made and called “sastras”. The all-inclusive term given to these three things (sutras, precepts, and sastras) is the “Tripitaka” or “three baskets,” in other words, containers in which the sutras, precepts, and sastras are stored.
Later, the total amount of Buddhist literature became extremely vast and for that reason was referred to as the “whole Buddhist canon.”
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