Beam

A beam is the line that goes between the stems of (normally) consecutive notes which are of note length quaver or less
The only purpose of a beam to to assist the easy readability of notes of short duration
There are various rules of grouping which give guidance on which notes are joined and where gaps are left. Gaps are nearly always left between beats and sometimes between subdivisions of beats
There are various rules about the slant of beams which publishers use to help make music more easily readable
- The beam slants in the direction of the notes, or if there are different directions within a group, from the first to the last of a group.
- Horizontal beams are used in a number of cases.
- Lengths of stems are adjusted to reach the beams, because beams are generally made not to slant too much.
In the example below, the quavers, semiquavers and demisemiquavers are beamed together in full beats or half-beats, for ease of readability. Notice how stems are lengthened or shortened in the last two groups to keep the beams at a reasonable angle.
In some types of music, particularly in complex piano music, beams can join notes on different staves, and can even have rests interpolated