What is co terminal?

Co-terminal angles are angles that share the same terminal side when drawn in standard position, meaning they differ by a full rotation of 360 degrees (or (2\pi) radians). For example, an angle of 30 degrees and an angle of 390 degrees are co-terminal because 390 degrees can be expressed as 30 degrees plus one full rotation (360 degrees). Co-terminal angles can be found by adding or subtracting multiples of 360 degrees (or (2\pi) radians).