What is a tessellation in math?

A tessellation is when a shape is repeated over and over creating an image without any spacing.... like triangles put together next to one another in an endless plane.

The tessellation is a repeating pattern of figures that covers a plane without any gaps or overlaps.

Honeycomb is a tessellation of hexagonal cells. You can see tessellation on some pavements.

Source: http://www.icoachmath.com/SiteMap/Tessellation.html