The Mahābhārata is one of the two major Sanskrit epics of ancient India, the other being the Rāmāyaṇa.

The Mahābhārata is an epic narrative of the Kurukṣetra War and the fates of the Kaurava and the Pāṇḍava princes. It also contains philosophical and devotional material, such as a discussion of the four "goals of life" or puruṣārtha (12.161). Among the principal works and stories in the Mahābhārata are the Bhagavadgītā, the story of Damayantī, an abbreviated version of the Rāmāyaṇa, and the story of Ṛṣyasringa, often considered as works in their own right.

Traditionally, the authorship of the Mahābhārata is attributed to Vyāsa. There have been many attempts to unravel its historical growth and compositional layers. The oldest preserved parts of the text are thought to be not much older than around 400 BCE, though the origins of the epic probably fall between the 8th and 9th centuries BCE. The text probably reached its final form by the early Gupta period (c. 4th century CE). The title may be translated as "the great tale of the Bhārata dynasty". According to the Mahābhārata itself, the tale is extended from a shorter version of 24,000 verses called simply Bhārata.

The Mahābhārata is the longest epic poem known and has been described as "the longest poem ever written". Its longest version consists of over 100,000 śloka or over 200,000 individual verse lines (each shloka is a couplet), and long prose passages. About 1.8 million words in total, the Mahābhārata is roughly ten times the length of the Iliad and the Odyssey combined, or about four times the length of the Rāmāyaṇa. W. J. Johnson has compared the importance of the Mahābhārata in the context of world civilization to that of the Bible, the works of Shakespeare, the works of Homer, Greek drama, or the Qur'an.

The epic is traditionally ascribed to the sage Vyāsa, who is also a major character in the epic. Vyāsa described it as being itihāsa (history). He also describes the Guru-shishya parampara, which traces all great teachers and their students of the Vedic times.

The first section of the Mahābhārata states that it was Gaṇeśa who wrote down the text to Vyasa's dictation.

The epic employs the story within a story structure, otherwise known as frametales, popular in many Indian religious and non-religious works. It is first recited at Takshashila by the sage Vaiśampāyana, a disciple of Vyāsa, to the King Janamejaya who is the great-grandson of the Pāṇḍava prince Arjuna. The story is then recited again by a professional storyteller named Ugraśrava Sauti, many years later, to an assemblage of sages performing the 12-year sacrifice for the king Saunaka Kulapati in the Naimiśa Forest.

The text has been described by some early 20th-century western Indologists as unstructured and chaotic. Hermann Oldenberg supposed that the original poem must once have carried an immense "tragic force" but dismissed the full text as a "horrible chaos." Moritz Winternitz (Geschichte der indischen Literatur 1