Eighth notes are a musical notes printed on sheet music used to determine the amount of notes per measure and rhythm of the entire musical arrangement. Eighth notes always consists of a half of a normal beat in each measure. Eighth notes occupies a half of a beat such as in 4/4 time where eight eighth notes notes takes up one measure, hence the name eighth note. Depending on the type of time signature printed on sheet music, the amount of eighth notes in each measure can vary from one musical arrangement to another.