Replication is a common term in multiplayer games. But what does replication mean in a game? Before learning replication, we first need to know what is meant by replica. A replica is a copy that looks exactly like the original one. Sometimes we see FIFA World Cup replicas brought to some events instead of the actual ones. In game development, if any variable updates everywhere simultaneously, then it's called replication. Like here, the value of the temperature variable is the same everywhere, which is 40. Now, Why we need replication in Game ? The answer is Very Easy Imagine you guys are playing pubg with this man in the same lobby. suddenly, the player died. Then the isplayerDead variable will become true for the player, and this variable is replicated enabled. So all of you will get a notification about this situation. In Unreal Engine , This notification goes through RepNotify