Before answering the question about what is a mitre saw and what is it used for we’ll begin with an answer to another different but related question, what is a mitre?
A mitre, or a miter joint as it is sometimes referred to is a joint that is made by cutting into each of two different parts (e.g. of wood) that are to be joined. The cut is often made at a 45° angle, thus forming a corner, if the other piece is also cut at 45° the two pieces joined together will form a 90° angle. This is the most common type of cut produced, however other cuts can be and are often required. An example of a mitre joint would be as used in a picture frame or door frame.
Image above shows a mitre joint in some piping, made using a mitre saw
So following on from the above explanation a mitre saw is used to cut mitre joints and crosscuts. Mitre saws were first developed using manual labour to power them, these days where speed, efficiency and clean cuts are required it is more common to find electric mitre saws in use. Mitre saws use a spinning blade to make these cuts.