Open means open to everyone. A textbook becomes “open” when its copyright-holder grants usage rights to the public through an “open license,” which typically includes the right to access, reformat, and customize it at no additional cost. It’s important to note that the open textbook author retains the copyright to the content, not the publisher as is traditionally the case.
Open textbooks look much like any other textbook
Hard copies of open textbooks look much like traditional texts. The primary difference is the price: open textbooks are also accessible online at no cost and the hard copies are optional and affordably priced.
There are lots of them
Thousands of open textbooks already exist and more are on the way.
Author payment varies
Open publishing models are still evolving, so author payment varies. Some are paid royalties on print sales, some receive grant support, and others choose to write on their own time.
The quality is comparable to any other textbook
Many open textbooks are developed through traditional peer review, others are vetted by experts. As with any textbook, the instructor is the final judge of whether an open textbook meets the needs of the course.