Textbook 2022-2023: The textbook for the regular class is BJU Biology (4th ed). This is an excellent Biology book, and there are lots of used ones available online. Do not buy the 5th edition, as it is a completely different book! (and the publisher has cheapened it a lot). Those taking the AP version of the class will instead be using OpenStax Biology (2nd edition), which you can download for free or buy an actual copy of online (recommended). The OpenStax website also has a book called "Biology for AP Courses" which is exactly the same book word-for-word, but with a lot of extra "bloat" pages which I don't find useful, but it's up to you. You can take a peek at both versions at OpenStax.org before purchasing. The Princeton AP Review book is optional but is helpful for exam prep starting around March (make sure you get the most up to date version, of course).