What does contrary motion refer to in musical terms?

In musical terms, contrary motion refers to the movement of two or more musical lines or voices in opposite directions. This means that when one line ascends in pitch, the other descends, or vice versa. This technique is often used to create balance and interest within a composition, enhancing the overall texture of the music.

Contrary motion can be particularly effective in counterpoint, where multiple melodies are played simultaneously. It helps to create a sense of conversation between the musical lines, allowing them to complement each other while maintaining distinct identities. This motion contrasts with parallel motion, where lines move in the same direction, and is an essential concept when studying harmony and voice leading.