A triangle wave is a type of non-sinusoidal waveform that has a triangular shape. It is characterized by a linear rise and fall, creating a repeating pattern of peaks and valleys. Triangle waves are commonly used in electronics and signal processing due to their simple harmonic properties. In terms of frequency, triangle waves contain a fundamental frequency and a series of odd harmonics. They are often used in synthesizers and audio applications to create unique sounds. The shape of the wave can affect the timbre of the sound produced, making it a popular choice among musicians and sound designers.