Musical note

A note in musical theory denotes a sound of constant pitch lasting for a specified time.

In western music, notes are assigned alphabetic names (A, B, C etc...) which are separated in pitch by a certain frequency called a tone. When written out as score each tone is assigned a rung on the stave:

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Tones can be further divided into semitones, which have the value of half a tone. Because the lines on the stave only distinguish between tones, notes are modified by the use of accidentals. The two main accidentals are sharps and flats; these respectively raise or lower the pitch of a note by a semitone.