OpenStax CNX

OpenStax CNX is a free online library full of educational materials. It has textbooks, articles, and other resources written by authors, teachers, and professors. All of the material is free to use and share. It's like a library - you can go online and find books, articles, and other resources that can help you learn. The books and articles are written in an easy-to-understand way and the resources are organized by subject and level to make it easy to find what you're looking for.