A way to keep track of changes across multiple systems. Time can drift between systems and can result in not knowing which change was the latest. A lamport clock keeps an int of the version and increase on each change. If a system sees a higher version it will select it.
One issue is if there is a conflict between clock versions. One solution is to decide a winner proactively and let the other get its settings. For example, when a conflict happens letting the server version win, get bumped and then push that back to the client.