Linked from
The 16 pages that link to Tessellation, each with the reason it gives.
PolygonRelated: Polygonal tiles can fit together to cover a plane.
Interior angleRelated: Angles around each tiling vertex must combine to a full turn.
M. C. EscherRelated: Repeated interlocking figures became a central structure in Escher’s prints.
Chuck CloseRelated: Close’s repeated cells divide portrait surfaces into a dense, ordered pattern.