Duple time

Duple meter (or duple metre, also known as duple time) is a musical metre characterized by a primary division of 2 beats to the bar, usually indicated by 2 and multiples (simple) or 6 and multiples (compound) in the upper figure of the time signature, with 2
2 (cut time), 2
4, and 6
8 (at a fast tempo) being the most common examples. Though it must, the upper figure being divisible by two does not of itself indicate duple metre; for example, a time signature of 6
8 usually indicates compound duple metre though it may locally emphasize simple triple, such as the famous example of Leonard Bernstein's song "America" from West Side Story.

4
4 is the most common time signature in rock, blues, country, funk, and pop. Although jazz writing has become more adventurous since Dave Brubeck's seminal Time Out, the majority of jazz and jazz standards are still in straight four time.

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