A more thorough explanation:

A permit is an official document that allows someone to do something. It is usually issued by a government agency, such as a state or city, and requires a fee to be paid.

For example, a firearms permit allows the holder to buy, own, possess, or carry a firearm subject to certain conditions. Another example is a building permit, which allows someone to construct a building or make changes to an existing one.

These examples illustrate how a permit grants permission to do something that would otherwise be prohibited. Without a firearms permit, it would be illegal to own or carry a firearm. Without a building permit, it would be illegal to construct a building or make changes to an existing one.