_3RR abbreviates _three-revert rule__. In any large public wiki implementing this rule, after any version of a document is restored three times with no change (no additional sources, no response to the allegations raised therein, no modification of terms), a fourth effort to do that is defined as a bad edit.

Accordingly, one of the versions censored or "clobbered" - similar to an edit conflict - will be restored. A senior editor will temporarily lock pages and if necessary approve versions to ensure that only an actual product of debate by edit appears as if published. The talk page usually becomes the only way to debate edits until there is some indication that the trolls seeking to impose only a single fixed point of view are willing to cooperate with an open editorial process.

This is a wiki best practice.