When Salman Khan began posting videos on YouTube more than a decade ago, the Silicon Valley entrepreneur had no idea of the celebrity he would gain, nor the impact he would have. His online tutorials in math ... were made for friends and family struggling in school. But his audience quickly grew. Before long, Khan had quit his day job in finance to carry out a goal of delivering free Internet instruction to the world. His educational website was called Khan Academy. On Tuesday night, Khan ... was presented the fourth annual Visionary of the Year Award, an honor announced by The San Francisco Chronicle. Khan Academy today has more than 62 million registered users in nearly 200 countries. His voice, which still narrates many of the tutorials, is widely recognized, and students and parents often stop him on the street to thank him for providing an assist at school or work. Since its launch in 2008, Khan Academy has broadened its online course load to include nearly every school subject from science to art and from the kindergarten to college levels. Khan's Mountain View nonprofit has grown from just him to more than 150 employees. Perhaps most impressive is that the schooling has remained entirely free. With the admirable mission of providing a world-class" education to anyone anywhere, Khan has attracted financial support from well-heeled donors, including the Bill and Melinda Gates Foundation, Google and Bank of America.