Music Theory Resources
The organization of time in music is just as fundamental (if not more so) than the system of pitches. Melodies are shaped just as much by their rhythms as they are by their melodic contours, and harmony depends on certain pitches being played synchronously. Many percussion instruments don't produce definite pitches at all, making them solely rhythmic instruments. The foundation of all rhythm is the beat.
The steady pulse, or beat, provides the framework for all rhythm in music. We dance to the beat, a conductor keeps the beat for an orchestra, and a metronome clicks the beat. The vast majority of music has a beat, even if sometimes it is not easy to follow.