A protractor, a transit level, an adjustable triangle and a speed square are all tools for measuring angles. Some tools are specific to certain professions.
A protractor is a ruler with a semicircle that students of geometry use to measure angles. A transit level uses a movable telescope and a rod to measure a horizontal level and angle of inclination. An adjustable triangle measures angles up to 90 degrees with its adjustable hinged edge.
A speed square works by being placed along a board's edge. It indicates angle measurements up to 60 degrees. Carpenters often use speed squares in their work.