Back in the day of typewriter, it was a dream to have a personal computer in every house because of the very expensive price. But Bill Gates and his classmates, Paul Allen about to change the paradigm. They are dropouts from Harvard University and then became the co-founders of Microsoft on 1975.On 1980, IBM and Microsoft had a first contract for making an Operating System for IBM PC. And they came up with MS-DOS. MS-DOS is like a brain for computers, it syncs hardware and software to work together. MS-DOS was a big success, because they believed that making their products on every computers was best strategy. Not like their rivals, Apple, they only made their Operating System exclusive to their devices up until now.But MS-DOS was still odd to a many consumers. Then on 1985, Microsoft launched it’s first Operating System with a user interface, they called it Windows 1.0. It features a simpler and easier way to use a computer compared to the old MS-DOS. Users were using a mouse to point and click through the interface, instead of typing commands like in the MS-DOS.Microsoft continued to innovate on Windows. On 1988, Microsoft became the largest PC software company. And on 1990, Microsoft launched it’s first office suites, called Microsoft Office. It’s an applications that helped people to work easier, like Microsoft Word and Microsoft Excel. Windows 3.0, as well Windows 3.1 sold ten million copies 2 years after their launch, it was the highest sales on Windows at that time. Windows and Microsoft Office became mainstream in every people’s computers.One of Microsoft’s biggest innovation was Windows 95. It sold seven million copies just only its first five weeks. One of the amazing feature was what we called internet. As internet growing, the PC sales was also grow. Microsoft’s share was peak and became one of the most valuable company. But Microsoft never stop to innovate more and moreIt also made their co-founders Bill gates, became the world richest man.