Dynamics
Dynamics are indicators of the relative intensity or volume of a musical line.

Pianississimo
Extremely soft. Very infrequently does one see softer dynamics than this, which are specified with additional ps.
Extremely soft. Very infrequently does one see softer dynamics than this, which are specified with additional ps.

Pianissimo
Very soft. Usually the softest indication in a piece of music, though softer dynamics are often specified with additional ps.
Very soft. Usually the softest indication in a piece of music, though softer dynamics are often specified with additional ps.

Piano
Soft; louder than pianissimo.
Soft; louder than pianissimo.

Mezzo piano
Moderately soft; louder than piano.
Moderately soft; louder than piano.

Mezzo forte
Moderately loud; softer than forte. If no dynamic appears, mezzo-forte is assumed to be the prevailing dynamic level.
Moderately loud; softer than forte. If no dynamic appears, mezzo-forte is assumed to be the prevailing dynamic level.

Forte
Loud. Used as often as piano to indicate contrast.
Loud. Used as often as piano to indicate contrast.

Fortissimo
Very Loud. Usually the loudest indication in a piece.
Very Loud. Usually the loudest indication in a piece.

Fortississimo
Extremely Loud.
Extremely Loud.

Crescendo
A gradual increase in volume.
Can be extended under many notes to indicate that the volume steadily increases during the passage.
A gradual increase in volume.
Can be extended under many notes to indicate that the volume steadily increases during the passage.

Diminuendo
Also decrescendo
A gradual decrease in volume. Can be extended in the same manner as crescendo.
Also decrescendo
A gradual decrease in volume. Can be extended in the same manner as crescendo.