A right triangle is a type of triangle that has one angle measuring exactly 90 degrees. This right angle distinguishes it from other triangles, which can have acute (less than 90 degrees) or obtuse (more than 90 degrees) angles. The side opposite the right angle is called the hypotenuse, while the other two sides are referred to as the legs. Right triangles are important in various fields, including geometry, trigonometry, and architecture. They follow the Pythagorean theorem, which states that the square of the hypotenuse's length is equal to the sum of the squares of the lengths of the other two sides.