Thousands of books have been removed from schools and libraries over the past several years, often accompanied by stormy public meetings and acrimonious debate. But there is a quieter way books have been pulled from libraries — a process called weeding.

The practice is standard for librarians, a regular part of keeping their collections current. Traditionally, weeding involves removing books that are damaged, out of date or haven’t been checked out in a long time. This makes room for new editions and titles that are of more interest to the community.

Now, three years into surge in challenges and removals of books from libraries, weeding is sometimes being used to remove books because of the viewpoint they express or the story they tell. The issue is now working its way through the court system.

Advocates say that, increasingly, administrators and library board officials are using this approach to avoid the public spectacle of formally pulling them because of their content.

“When you remove a book because you believe it’s critical race theory, or portrays L.G.B.T.Q. lives or because you believe it’s too vulgar,” said Deborah Caldwell-Stone, Director of the American Library Association’s Office for Intellectual Freedom, “that’s not weeding. That’s censorship.”

In recent years, the number of books that have been restricted or removed has surged around the country, fed in part by conservative organizations, lists of books that circulated on social media and state laws that have decided what kinds of books are appropriate for children.