The English Wikipedia introduced its pending changes system in 2010. The initial implementation began as a two-month trial on June 14, 2010.
Pending changes are part of the Flagged Revisions system, which allows edits to selected pages to remain unseen by readers until reviewed by an editor with the relevant permissions. The feature was intended to add protection against vandalism and inaccurate changes without completely blocking ordinary users from editing.
The trial did not immediately become a permanent, broadly applied policy. After discussion in 2011, pending changes were initially removed from all articles. A later 2012 discussion reached consensus to implement the feature again. This history explains why 2012 can appear in accounts of pending changes: it marks a later policy decision, not the original English Wikipedia introduction.