Friction is the force that stops things from moving. You only notice friction when you try to move. You can think of friction as a kind of sticky force, a kind of invisible glue.

It is quite hard to overcome this force, which is why you have to put in effort (a push or a pull force) in order to get something moving. Once it is moving, keeping it moving much easier. So, for example, it is much more efficient on fuel to keep a car going than to keep stopping and starting it in traffic.