A protractor is a simple tool used to measure angles in degrees. It usually has a flat, semi-circular shape with markings from 0 to 180 degrees. You can find protractors in classrooms, where students use them in subjects like mathematics and geometry to help draw and measure angles accurately. To use a protractor, you place the center hole over the angle's vertex and align one side of the angle with the zero line. Then, you can read the measurement where the other side crosses the numbered scale. Protractors are essential for anyone working with angles, including engineers and architects.