Breath mark
A comma above the staff for taking breath or a break.
What it means
The breath mark instructs the performer to take breath at this place. It thereby stands at the border between technical instruction and musical articulation: where breath is taken, one phrase ends and the next begins. The time needed for it is as a rule taken from the preceding note value, that is, the last note is shortened a little; the bar is thereby not thrown off balance.
In the notation
Usual is a small comma above the top line of the staff, occasionally also an apostrophe. In wind and vocal parts it is found regularly; in string parts the same sign frequently stands for a lifting of the bow or a bow change. From the sign of the caesura with its two oblique strokes it differs in meaning: the caesura interrupts the flow perceptibly for all involved, the breath mark articulates within one part without touching the tempo. The fermata too is to be distinguished — it lengthens, the breath mark shortens.
Musical use
In vocal music the breathing follows first of all the text: a breath mark in the middle of a word would run counter to sense, whereas at a punctuation mark it is natural. With long lines that a single singer or wind player cannot manage without interruption, the choir or the section distributes the breathing in a staggered way, so that the sound never breaks off. Composers set breath marks partly as compulsory, partly as a suggestion; in older editions they are often missing entirely, and the articulation follows from text and phrasing slurs.
Performance practice
Settle the breathing places before practising and enter them in pencil, instead of deciding them anew each time — irregular breathing is at once audible in performance. Take the time for the breath from the previous note and not from the following one, or you come in late. With staggered breathing in an ensemble: do not breathe where your neighbour breathes, and avoid the place immediately before a phrase climax. Practise difficult long arcs at first deliberately with an extra breath mark and delete it as soon as the breath suffices.