Off-mesh link
A hand-placed connection that stitches together two otherwise separate parts of a navmesh so an agent can jump, climb or teleport between them.
A navmesh only describes surfaces an agent can walk on. Gaps, ledges, ladders and doorways cut it into islands the pathfinder cannot cross — it sees no edge to follow. An off-mesh link is drawn in by hand (or generated) as a directed bridge between two points: "drop down here", "climb up there".
The link carries a traversal cost like any other edge, so A* can weigh a shortcut over a fence against walking around. When the agent reaches it, it leaves ordinary navmesh-following and plays a dedicated animation — a jump, a vault, a zipline — before resuming on the far side. Unity calls them Off-Mesh Links, Unreal a Nav Link Proxy.