The meter of a piece of music is the arrangment of its rhythms in a repetitive pattern of strong and weak beats. This does not necessarily mean that the rhythms themselves are repetitive, but they do strongly suggest a repeated pattern of pulses. It is on these pulses, the Beats and Measures of the music, that you tap your foot, clap your hands, dance, etc.
Some music does not have a meter. Ancient music, such as Gregorian chants; new music, such as some experimental twentieth-century art music; and Non-Western music, such as some native American flute music, may not have a strong, repetitive pattern of beats. Other types of music, such as traditional Western African drumming, may have very complex meters that can be difficult for the beginner to identify.
But most Classifying Music music has simple, repetitive patterns of beats. This makesmeter a very useful way to organize the music. Common notation, for example, divides the written music into small groups of beats called measures, or Beats and Measures. The lines dividing each measure from the next help the musician reading the music to keep track of the Rhythm. A piece (or section of the piece) is assigned a time signature that tells the performer how many beats to expect in each measure, and what type of note should get one beat. (For more on reading time signatures, please see Time Signature.)
Conducting also depends on the meter of the piece; conductors use different conducting patterns for the different meters. These patterns emphasize the differences between the stronger and weaker beats to help the performers keep track of where they are in the music.
But the conducting patterns depend only on the pattern of strong and weak beats. In other words, they only depend on "how many beats there are in a measure", not "what type of note gets a beat". So even though the time signature is often called the "meter" of a piece, one can talk about meter without worrying about the time signature or even being able to read music. (Teachers, note that this means that children can be introduced to the concept of meter long before they are reading music. See Meter Activities for some suggestions.)