In his junior year, Gates left Harvard to devote his energies to Microsoft, a company he had begun in 1975 with his childhood friend Paul Allen. Guided by a belief that the computer would be a valuable tool on every office desktop and in every home, they began developing software for personal computers. Gates' foresight and his vision for personal computing have been central to the success of Microsoft and the software industry.

　　Under Gates' leadership, Microsoft's mission has been to continually advance and improve software technology, and to make it easier, more cost-effective and more enjoyable for people to use computers. The company is committed to a long-term view, reflected in its investment of approximately $6.2 billion on research and development in the 2005 fiscal year.

　　Gates has donated the proceeds of both books to non-profit organizations that support the use of technology in education and skills development.

　　In addition to his love of computers and software, Gates founded Corbis, which is developing one of the world's largest resources of visual information - a comprehensive digital archive of art and photography from public and private collections around the globe. He is also a member of the board of directors of Berkshire Hathaway Inc., which invests in companies engaged in diverse business activities.

Philanthropy is also important to Gates. He and his wife, Melinda, have endowed a foundation with more than $28.8 billion (as of January 2005) to support philanthropic initiatives in the areas of global health and learning, with the hope that in the 21st century, advances in these critical areas will be available for all people. The Bill and Melinda Gates Foundation has committed more than $3.6 billion to organizations working in global health; more than $2 billion to improve learning opportunities, including the Gates Library Initiative to bring computers, Internet Access and training to