Dynamics 
Dynamics are terms or symbols that define the level in which the music is to be played. The dynamics listed below are in order from soft to loud.
Dynamic  Notated  Performed as 
Pianissimo  pp  Very soft
Piano  p  Soft
Mezzo Piano  mp  Moderately soft
Mezzo Forte  mf  Moderately loud
Forte  f  Loud
Fortissimo  ff  Very loud