Khan Academy

Khan Academy is an American non-profit educational organization created in 2008 by Salman Khan. Its goal is creating a set of online tools that help educate students. The organization produces short lessons in the form of videos. Its website also includes supplementary practice exercises and materials for educators. It has produced over 8,000 video lessons teaching a wide spectrum of academic subjects, originally focusing on mathematics and sciences. All resources are available for free to users of the website and application.
As of 2018, over 70 million people use Khan Academy, out of which 2.3 million students use it to prepare for SAT. As of February 2022, the Khan Academy channel on YouTube has 7.11 million subscribers and Khan Academy videos have been viewed more than 1.94 billion times.