A tessellation is a pattern in which a shape or tile fits together with copies of itself to fill the plane with no gaps or overlaps. One type of tessellation is formed with sides of center-point rotation, that is, one half of an edge is rotated 180 degrees to form the other half. If a square template is made with sides of identical center-point rotation, there are exactly four shapes that are possible.

If these shapes or tiles are fit together not edge to edge but vertex to vertex, the result is a checkerboard-like pattern of tiles and voids. However, the voids have four edges formed by the four possible shapes that the tiles can have, so the voids are limited to the same four shapes that that make up the tiles. The FabFours have 22 tile families that allow a wide variety of fascinating patterns. They form one, two, three, and four tile tessellation. Eleven of the seventeen symmetry groups can be formed with these patterns.

Each tile family two of the shapes have two possible orientations, one shape has four possible orientations, and one has eight, for a total of 16 tiles. Each font has two families, one on letters A-P the other on a-p. For some of the families there are also other tiles using the same edge but using triangular and hexagonal templates.

To get proper results, the leading must be set equal to the point size of the font.

I discovered these fabulous families and their decorative possibilities as I was working on a book about tessellations. I have not been able to find anyone else who has written about these families of four and their decorative possibilities when arranged vertex to vertex.