Salman Khan is a pioneer of online learning, having founded the Khan Academy in 2008. The online educational website features more than 5,500 mini-lectures, free of charge, to anyone in the world. The videos are hosted on YouTube and teach a variety of subjects, such as: mathematics, history, healthcare, medicine, finance, physics, chemistry, biology, astronomy, economics, cosmology, organic chemistry, American civics, art history, macroeconomics, microeconomics, and computer science. They are available in several languages through subtitle translations. The Khan Academy channel on YouTube has more than 6.7 million subscribers and the Khan Academy videos have been viewed more than 1.8 billion times. Khan published his international best seller, The One World School House, in October 2012.