Quarternote

Quarternote, also known as quarter note in American usage and crotchet in British usage, is a basic musical note in Western notation. It represents one quarter of the duration of a whole note, making it a standard unit of time in common-practice notation.

It is written as a filled oval note head with a straight stem and no flags. In standard notation, quarternotes are not beamed together; two or more may appear consecutively separated by bar lines. The corresponding rest is the quarter rest, which resembles a small vertical squiggle.

In common time, four quarternotes equal a whole note and thus one measure of 4/4 often contains four beats. The exact duration in seconds depends on tempo; at 60 beats per minute, a quarternote lasts one second; at 120 BPM, it lasts half a second.

Quarternotes are among the most frequent note values in melodies and rhythms, used in many musical styles, from classical to popular music. They can be tied to extend duration, and a dot after a quarternote adds half of its value, giving a dotted quarternote. In simple meters, groups of four quarternotes help define the structure of a measure in 4/4.

Terminology varies by region: quarternote in some contexts, quarter note in American English, crotchet in British English. The concept arose with the development of modern musical notation, providing a stable unit of time for written music and replacing some earlier long-note values.