Delaunay triangulation
A triangulation that maximises the smallest angle by ensuring no point lies inside any triangle's circumscribed circle.
Boris Delaunay stated the condition in 1934. Of all the ways to triangulate a point set, Delaunay picks the one that avoids long, thin "sliver" triangles — the empty-circle condition forces triangles as well-shaped as possible. It is the geometric dual of the Voronoi diagram.
In games and graphics it's used for terrain (TIN models from height data), for generating well-formed meshes, and as a basis for navmeshes. Common algorithms are Bowyer–Watson (incremental circle tests) and divide-and-conquer. Unlike ear clipping, it cares not just about splitting a surface into triangles, but about the quality of those triangles.