A grid is a regularly repeating pattern of lines separating some shape or an entire plane into small cells. The most common grid is a square grid in which 2 sets of equally-spaced parallel lines are perpendicular to each other. You can also have triangular grids, hexagonal grids, polar grids (which have a set of concentric circles and a number of lines passing through their common center), etc.

Often, grids are marked with coordinates.