In the beginning, Salman Khan, was simply trying to help his cousin learn mathematics over the Internet. Soon others began seeking his help and he started posting Youtube videos. The popularity of his videos grew and seeing the large amount of people in need, he decided to create the Khan Academy website as a way to consolidate the lessons.
Starting from the topic of mathematics, Khan Academy has branched into the sciences and humanities. The site is recognized as a valuable educational resource and has received several grants and other donations from notable sources. You can go through some in-depth training in higher level mathematics, bank practices, or settle into some art history. Available worldwide, all for free.