Vedanta is a formal school of Hindu philosophy founded by sage Badarayana. The word ‘Vedanta’ is derived from etymology of Veda + anta where “Veda” refers to the oldest and sacred scriptures of Hinduism called [wiki]Vedas[/wiki], and ‘anta’ means end of or culmination. Therefore it means the end of or culmination of the Vedas, or rather the culmination of the knowledge(jnana) taught in the Vedas. Vedanta expands upon the philosophy of Brahmanism(see [wiki]brahman[/wiki]) as presented in the Vedas and Upanishads and presents it rationally. In a way it can be seen as an exegisis of the Vedas, but unlike a normal theological discourse, it attempts to offer rational arguments to prove the Vedic concepts, thus making it more philosophical in character.
Vedanta is the most popular school of Hindu philosophy and has more or less defined the course of Hindu philosophy over the last 2000 years. Popular Hinduism is largely based on Vedanta philosophy. There are several different sects of Vedanta who interpret the philosophy of Brahmanism differently. The three main ones are: [wiki]Advaita[/wiki], [wiki]Dvaita[/wiki] and [wiki]Viseshadvaita[/wiki]. Respectively, non-dualism, dualism and special non-dualism. Of these by far the most popular is Advaita and has been very influencial in shaping modern Western spirituality.
All Vedanta schools observe as their central canon the Prasthanatrayi(the three core texts) consisting of the Brahama sutras attributed to sage Badarayana which are considered the logical starting point, the Upanishads and in particular the 13 major Upanishads that all Vedanta sects have commented on and are considered as the primary texts, and the Bhagvad Gita which is considered the practical text which illustrates how Vedanta is lived.