MEASURE

In musical notation, a bar (or measure) is a segment of time between two bar lines defined by a given number of beats of a given duration. Typically, a piece consists of several bars of the same length, and in modern musical notation the number of beats in each bar is specified at the beginning of the score by the top number of a time signature (such as 4/4).

The word bar is more common in British English, while the word MEASURE is more common in American English, although musicians generally understand both usages. In American English, although the words bar and measure are often used interchangeably the correct use of the word 'bar' refers only to the vertical line itself, while the word 'measure' refers to the beats contained between bars.