A miter saw or mitre saw is a saw used to make accurate crosscuts and miters in a workpiece by positioning a mounted blade onto a board. A miter saw in its earliest form was composed of a back saw in a miter box, but in modern implementation consists of a powered circular saw that can be positioned at a variety of angles and lowered onto a board positioned against a backstop called the fence.Powered miter saws also cut bevels into a work piece by adjusting the vertical tilt axis of upper portion of the machine while the table lays flat horizontally. A miter saw for which the axis can be tilted in a single direction is known as a single compound miter saw. If the axis can tilt both left and right, it is known as a double bevel compound miter saw. Some are equipped with a sliding rail system or have a pivot arm to cut wider work pieces when laid flat on the table of the saw and flush against the fence. This is known as a sliding compound miter saw.Miter saws are primarily used for cutting wood trim and molding, but also can be used to cut metal, masonry, and plastics, provided the appropriate type of blade is used for the material being cut.