Microsoft was founded by Bill Gates and Paul Allen and became one of the world’s largest firms by market capitalization.
Gates and Allen established Microsoft in 1975 after developing and promoting a version of the BASIC programming language for the Altair 8800 microcomputer. The company initially focused on software rather than manufacturing computers.
Microsoft’s major expansion came through MS-DOS and Windows, which became dominant operating systems for personal computers. Its Office productivity suite added another durable source of revenue. Later, Azure cloud computing, enterprise software, gaming, and professional networking broadened the business.
Market capitalization changes daily with the share price, so rankings among the largest companies can change frequently. Microsoft is often compared with Apple, Saudi Aramco, Alphabet, Amazon, and other mega-cap firms, but its identity is distinct from IBM, an older technology company that Microsoft did not found.