A choke point is narrow part of a PvE or PvP map which will force your team to cluster together when passing through. Passing through a choke point against enemies of player teams who have AoE spells is often considered folly because your entire team will be caught in the AoE damage. Many teams choose to wait on their side of the choke point rather than pass through it and get caught in their enemy's fire. Choke points are also common spots to place traps or stop enemy's advance (or retreat) by body blocking.
Choke points can greatly benefit PvE play, especially in Hard Mode, as it gives AoE damage a chance to take out durable enemies before they have a chance to fight back. Use pulling and tanking to use the enemy AI to your advantage. Sometimes these points are exploited in farming.