In math, a net is a two-dimensional pattern that can be cut and folded to form a three-dimensional space figure.
In the figure below, you can see the net of a cube and its corresponding three-dimensional figure.
Notice that the number of surfaces on a solid figure has to match the number of regions in its net.
In the figure below, you can see the net of a triangular pyramid and its corresponding three-dimensional figure.
Notice that all four triangles in the net are equilateral triangles