In this week's Newsround Extra Lizo Mzimba took a look at who's keeping an eye on you, and how CCTV is an attempt to make streets safer.
It's used in lots of different ways to fight crime. Cameras watch out for shoplifters, spot vandals and sometimes to record people committing acts of violence against each other.
You'll also come across CCTV in most schools - even some school buses.
Is it right?
But for cameras to protect you from crime they have to spend time spying on you, and some people feel that's not right.