Conflicts can occur in replication environments where multiple writers update a document concurrently, leading to inconsistencies. Couchbase Mobile uses Multi Version Concurrency Control (MVCC) to handle conflicts by assigning each document a unique revision ID and creating a Revision Tree. The Revision Tree represents the history of changes made to a document, with each revision being assigned a new revision ID. When a conflict occurs, Couchbase Mobile picks a "winner" among the conflicting revisions using specific criteria, such as the undeleted leaf revision on the longest revision branch. However, it is ultimately the application's responsibility to resolve conflicts by choosing between the picked winner and other conflicting revisions, potentially merging changes or deleting non-winning branches. The application must also ensure that unwanted leaf revisions are tombstoned to prevent database size issues.