Bounding volume hierarchy (BVH)
A tree of bounding volumes in which every node encloses its children, so whole branches can be dismissed with one test.
A BVH groups a scene's objects into a binary (or wider) tree. Each node carries a volume — usually an axis-aligned box — that contains everything beneath it. A query such as "what can this ray or box possibly hit?" tests the root first; if it misses, the entire subtree is skipped. In practice the cost drops from linear to roughly logarithmic.
The structure shows up anywhere you want to avoid touching everything: the broad phase of collision search, ray-tracing acceleration, and frustum culling of what the camera cannot see. Quality depends on how the tree is built — the surface area heuristic (SAH) is the standard choice — and on keeping it up to date as objects move, which is the hard part in dynamic scenes.