A tessellation unit is a TILE, which is a four-letter word. A tessellation is a pattern of shapes that fit together to form a larger shape without any gaps or overlaps. The tiles used in a tessellation are usually regular polygons, such as squares, triangles, and hexagons. Tessellations can be found in art, architecture, and nature. They are often used to create decorative patterns on floors, walls, and ceilings.