Born in London, William Jones' father (also named Sir William Jones) was a highly educated man: a mathematician who proposed the symbol π to represent the number 3.1415..., vice-president of the Royal Society, and a close friend of Sir Isaac Newton. The young Jones was a linguistic prodigy, learning Greek, Latin, Farsi, and Arabic at an early age. By the end of his life he was reported to be able to speak twenty-eight languages.
Though his father died when he was only three, Jones was still able to go to university. Graduating from University College, Oxford in 1764, he embarked on a career as a tutor and translator for the next six years. During this time he published Histoire de Nader Chah, a translation of a work originally written in Farsi. This would be the the first of numerous works on Persia, Turkey, and the Middle East in general.
For three years starting in 1770 he studied law, which would eventually lead him to his life work in India; after a spell as a circuit judge in Wales (and a fruitless attempt to resolve the issues of the American Revolution in concert with Benjamin Franklin in Paris), he was appointed to the Supreme Court of Bengal in 1783.
There he was entranced by Indian culture, a then-untouched field of European scholarship, and he founded the Asiatick (sic) Society of Bengal. Over the next ten years he would produce a flood of works on India, launching the modern study of the subcontinent in virtually every social science. He also wrote on the local laws, music, literature, botany, and geography, and made the first English translations of several important works of Indian literature.
Of all his discoveries, Jones is best known today for being the first to notice that Sanskrit bore a certain resemblance to Greek and Latin. In 1786's The Sanscrit Language he suggested that all three languages had a common root, and that further they might all be related in turn to Gothic and Celtic languages, and to Persian. This was the first evidence of the Indo-European language family, and was also the first important use of the technique of comparative philology.
Jones is also indirectly responsible for some of the feel of the English Romantic movement's poetry (including the likes of Lord Byron and Samuel Taylor Coleridge, as his translations of "eastern" poetical works were a source for that style.