What is parralel motion?

Parallel motion is a term used in music theory to describe a harmonic technique in which two or more melodic lines move together in the same direction but at different intervals. Parallel motion is often used in choral music, where the different voice parts will move together in parallel motion to create rich and harmonious chords. However, parallel motion can also be used in instrumental music, such as in the opening theme of Beethoven's Fifth Symphony, where the strings move in parallel fifths. While parallel motion can create a strong sense of unity and harmony in a piece of music, it can also create a sense of monotony if used excessively. As a result, many composers will vary the amount of parallel motion they use, alternating between parallel and contrary motion to create interest and variety in their music.