Microsoft began in 1975 when Bill Gates and Paul Allen wrote a BASIC interpreter for the Altair 8800, one of the first personal computers. Their bet — that the value would move from hardware to software — proved to be one of the most consequential calls in business history.
The deal that made an empire
The turning point came in 1981. IBM needed an operating system for its new Personal Computer; Microsoft supplied MS-DOS but, critically, kept the right to license it to others. When the market filled with IBM-compatible "clones", every one of them needed Microsoft's software. That single contract turned a small company into the gatekeeper of the PC era.
Windows and Office
Through the 1990s Windows put a graphical interface on the world's PCs and Office became the default way businesses wrote documents, ran spreadsheets and built presentations. At its peak Microsoft's software ran on the overwhelming majority of the world's computers — dominance that also drew landmark antitrust scrutiny.
The cloud, and then AI
After a period of missing mobile, Microsoft reinvented itself around the cloud. Azure, launched in 2010, grew into one of the largest cloud platforms, and the company shifted to subscriptions (Microsoft 365) and services. Its multibillion -dollar partnership with OpenAI then placed it at the centre of the generative -AI wave, wiring large language models into Windows, Office and developer tools — a second act few software giants ever manage.