T-square is defined as an instrument that is used for technical drawing purposes. The primary purpose of using T-square is to do technical drafting, drawing horizontal lines on the surface of a drafting table. It is also used as a guide or a set square to draw diagonal or vertical lines. The name is derived from the letter T as it resembles its structure. T-square comes in different sizes; the common lengths are 18, 24, 30, 36, and 42 inches. The main application of a T square is when they are measured and cut drywall. Cut drywall T squares are usually aluminum and have a 48-inch-long tongue. The higher-end table saws usually come with a T-square fence to get an accurate measurement. The table is attached to a rail on the front side of the table, unlike traditional fences, which clamp to both the front and rear of the table.