The Jataka Tales tell the story of the Buddha before he was the Buddha, following the being who would eventually achieve final awakening as Siddhartha Gautama back through hundreds of earlier existences, as a king, a monkey, a merchant, an elephant, an ascetic, a talking bird, moving freely between animal, human and divine form across the collection's five hundred and forty seven numbered stories. Each tale is built to illustrate a specific virtue, one of the ten paramitas, or perfections, generosity, patience, truthfulness, moral discipline and the rest, that the tradition holds a being must cultivate across countless lifetimes before becoming capable of full awakening. A generous prince who gives away everything he owns, an animal that sacrifices itself for others, a wise minister who tells an unwelcome truth at personal cost: the pattern repeats across widely different settings because the underlying lesson, not the specific plot, is the constant.
Structurally each tale in the canonical collection is genuinely brief, a set of verses embedded within the Khuddaka Nikaya, the fifth and most varied division of the Sutta Pitaka. What most readers actually encounter as "a Jataka tale," the fuller prose narrative that sets the scene, tells the story in detail and closes by identifying which character in the past-life story corresponds to which person in the Buddha's own final life, is a separate and later layer of commentary built around those verses rather than part of the verses themselves.