### Theory:

Imagine cutting open a match box across all of its edges, and laying the figure thus formed flat. The outline thus formed is called its net.
Net of a $$3-D$$ shape
The outline formed when a $$3-D$$ shape is cut open along its edges is called the net of a $$3-D$$ shape.

In other words, the net of an object is cut in such a way that it could be assembled into a $$3-D$$ shape anytime.

Example:
Let us look at the net of a cube.

Let us also look at the net of a cylinder.