Ludwig Wittgenstein (1889–1951) was an Austrian-British philosopher who worked primarily in logic, the philosophy of mathematics, the philosophy of mind, and the philosophy of language. His two major works, "Tractatus Logico-Philosophicus" and "Philosophical Investigations," respectively, contributed to analytic philosophy and the philosophy of language. Wittgenstein is considered one of the most important philosophers of the 20th century, challenging traditional ideas and significantly influencing contemporary thought.