Khan Academy | Free Online Courses, Lessons & Practice
Learn for free about math, art, computer programming, economics, physics, chemistry, biology, medicine, finance, history, and more. Khan Academy is a nonprofit with the mission of providing a free, world-class education for anyone, anywhere.
I am sure you know what bookmarks are - those strips of leather or crafted card used to mark a place in a book. Similarly, on the internet, users can use bookmarks to save their favorite pages to visit in future.