Water shut off valves are common in your plumbing system

The isolate certain sections of the plumbing system so it can be worked on and maintained.

There are different ways a valve can be attached to the pipe. The copper pipe in this video could be soldered back together, but there are other ways.

This video shows the use of compression fittings. Sharks tooth fittings are also commonly used these days.

Watch the video and see how easy it is to do.