At age nineteen (1975) Bill Gates and high school classmate Paul Allen formed Microsoft. By the 1980s Microsoft developed an operating system for IBM and created innovative software for Apple. Between 1978 and 1981 Microsoft revenue increased from $4 to $6 million. In 1983, 30% of personal computers were using Microsoft software.
Gates introduced Microsoft Windows and later it became the signature software for most PCs. By 1997, Microsoft delve into the internet market and included Explorer on every copy of Microsoft Windows.