What they are:
Wire cutters or diagonal pliers are other tool very much needed when handling wire, used to cut, oh surprise, wire like silver, copper or steel. In the market you will find many different blade models. The gauge of the wire that you are going to cut determines the size, and the type, of the wire cutter that you should be using. If you use a fine cutter on a heavy gauge wire you may destroy it at the very first cut!
What they are used for:
Obviously, to cut wire. Either to cut specific lengths or to trim off excess wire. They are not used to turn or grab anything, only cut. Some people use scissors to cut soft wire, this is not recommendable as it may damage the scissors.
They come in two styles: side cutters and top cutters.
Be careful when trimming off small pieces of wire, as it can hit you in the eye!
Keep cutters away from children.