Former president Barack Obama publicly joined the fight against censorship and book banning on Monday, posting a letter addressing the wave of book challenges and thanking librarians.

"Whether you just started working at a school or public library, or you've been there your entire career, Michelle and I want to thank you for your unwavering commitment to the freedom to read," he wrote. "All of us owe you a debt of gratitude for making sure readers across the country have access to a wide range of books, and all the ideas they contain."

In his Twitter and Instagram posts, Obama wrote, "Today, some of the books that shaped my life—and the lives of so many others—are being challenged by people who disagree with certain ideas or perspectives. And librarians are on the front lines, fighting every day to make the widest possible range of viewpoints, opinions, and ideas available to everyone."

At the end of the posts, he directed his followers to United Against Book Bans "to learn how you can support librarians and defend the right to read."

Read the full letter below.