Heesch tiling notation encodes the edge identifications of an asymmetric tile in an isohedral tiling. Traversing the tile boundary
gives a cyclic word whose symbols record how paired edges are related. A pair related
by a translation is denoted 
, a pair related by a glide, also
called a glide reflection, is denoted 
, and an edge paired to itself by a half-turn
is denoted 
.
A symbol 
records adjacent edges paired by a rotation through
degrees about their common endpoint.
The cyclic word is read up to a change of starting edge and reversal of orientation. Together with the incidences of the edge pairs, these symbols distinguish the 28 Heesch types of asymmetric isohedral tiles. Heesch tiling notation describes how copies meet; it is distinct from the Heesch number, which counts possible surrounding layers of a tile.
