Your lovely professors/instructors choose your Required textbooks. Required textbooks contain the basis of the course and will be referred to frequently. Alternative textbooks are variations of the required textbook that deliver the same content but in a different format.
For example, your instructor may have selected an eBook and access code as the Required Textbook. However they are also giving you an alternate option of the physical package of the book, which contains the print version of your textbook and digital access code as a package. If you’d prefer having the physical book rather than an eBook, you can select the print package as an alternate option. Alternate options provide students options for purchasing the course materials that best fit their learning needs and their budgets. Important note: you only need to buy ONE of either the Required textbook or its alternates, as either option is acceptable for your course.
If you want to be a boss, you can also read the optional textbooks, which are for additional reading on a particular subject. Optional textbooks aren’t required for your course, these are normally supplementary course materials that are recommended by your instructors.