ELI5: Explain Like I'm 5

Access control

Access control is like a game of tag; some people can tag (or access) certain places, while other people can't. To make sure the right people get access to the right places, there are rules like locked gates, passwords, and other security measures that only the people who are "it" can use. This way, we can make sure that only certain people can go certain places and that everyone else is kept out.