# Measure

Source: https://arcosounds.com/glossary/measure
Also known as: bar

**A measure, called a bar in British usage, is the span of music between two barlines, containing the number of beats set by the time signature.**

The measure is the unit that makes rhythm readable: it groups beats so that a player can see where the strong beat falls without counting from the start of the piece. In 4/4 every measure holds four quarter-note beats; in 3/4, three.

Orchestral parts number measures, usually every bar or every five, so a conductor can say "from bar 61" and fifty players find the same place. Rehearsal marks, letters or boxed numbers, do the same job at structural points, and a well-prepared part has both circled.

A pickup or anacrusis at the start of a piece is an incomplete measure, and it is conventionally not numbered; the first full measure is bar 1.

Canonical source: https://arcosounds.com/glossary/measure