[2] Squares are tools designed for marking and checking specific fixed angles, usually 90° or 45°, though most squares are exclusively for working with 90° angles.

Miter squares are usually made from two fixed parts, a stock and a blade (sometimes called a tongue).

The blade on a modern factory-made miter square is typically a thin piece of metal which is fixed at 45° onto or into the stock, forming a 'T' shape.

The stock is usually much thicker than the blade and is made from wood, metal or plastic.

[1] Other forms of miter square include the dovetail square, with the blade set at an angle suited to marking out dovetail joints, and the Japanese miter square, a flat piece of metal with a thin metal stock along one edge – similar in construction to a speed square.