In information visualization and graphic design, Truchet tiles are square tiles decorated with patterns that are not rotationally symmetric. When placed in a square tiling of the plane, they can form varied patterns, and the orientation of each tile can be used to visualize information associated with the tile's position within the tiling.

Truchet tiles were first described in a 1704 memoir by Sébastien Truchet entitled "Mémoire sur les combinaisons", and were popularized in 1987 by Cyril Stanley Smith.

The tile originally studied by Truchet is split along the diagonal into two triangles of contrasting colors. The tile has four possible orientations.

Some examples of surface filling made tiling such a pattern.

With a scheme:

With random placement:

A second common form of the Truchet tiles, from Smith (1987), decorates each tile with two quarter-circles connecting the midpoints of adjacent sides. Each such tile has two possible orientations.

We have such a tiling: