The marks that tell a performer how rather than what — how loud, how detached, how fast, how held. Grouped separately from the notes themselves because they answer a different question, and because almost all of them are relative: a piano marking in a solo and in a full orchestra are entirely different volumes, and nothing in the notation makes them comparable. Two members are genuinely disputed among editors, and their records say so rather than choosing.
A slanted lower-case p below the staff, instructing quiet playing.
A slanted lower-case f below the staff, instructing loud playing.
A long horizontal wedge opening to the right, meaning gradually louder.
A long horizontal wedge closing to the right, meaning gradually quieter.
A dot above or below a notehead, shortening the note without changing it.
A horizontal wedge above a note, instructing extra attack.
A short horizontal bar above a note, instructing its full length.
A dot beneath a shallow arc, holding a note or rest beyond its length.
A comma above the staff, marking where to breathe or lift.
A curved line joining notes of different pitch, played smoothly.
A curved line joining two notes of the same pitch into one sound.
The letters tr above a note, instructing rapid alternation with its neighbour.
A short zigzag above a note, instructing a single rapid alternation.
The abbreviation Ped. below the staff, instructing the pedal down.
8va above a dashed line, moving a passage an octave from where it is written.
A straight or wavy line between two notes, sliding continuously between them.
Slashes across a note stem, instructing rapid repetition.
A note value, an equals sign and a number, fixing the tempo exactly.
A grid of lines with dots, showing where fingers go on a fretted instrument.
A double bar line with two dots, marking a section to be played again.
A slanted S crossed by a diagonal with two dots, marking a return point.
A circle crossed by a vertical and horizontal line, marking a closing section.