Squares have been used for centuries to help builders and carpenters cut straight lines and accurate angles. Historically, they were made out of wood and were pretty basic, with no markings.
Since the most common angles are perpendicular angles, the square is made up of two timber or metal lengths joined together at a 90 degree angle. Many modern squares may also be stamped from a single piece of steel or aluminium.
These squares can range from small drawing types to large framing squares.
Some squares also include metric, imperial, or both metric and imperial graduations to help with measurements.