Quadtree
In plain terms
A tree that recursively divides 2D space into four quadrants.
Going deeper
A quadtree partitions a 2D area into quadrants, subdividing dense regions further, to index spatial data efficiently. It speeds up location and collision queries.
Under the hood
Adapts resolution to data density; enables fast spatial range and nearest-neighbor queries in 2D.
Examples
Image compression, collision detection, GIS, game spatial indexing.
Think of it like...
Like a map that zooms into quarters, then quarters of quarters, where detail is needed.