We need the softess to the loudest dynamic markings

• p or piano, meaning "soft."
• f or forte, meaning "loud" or "strong" also it can mean "deep".

More subtle degrees of loudness or softness are indicated by:

• mp, standing for mezzo-piano, meaning "moderately soft" and
• mf, standing for mezzo-forte, meaning "moderately loud".

Beyond f and p, there are also

• ff, standing for "fortissimo", and meaning "very loud" and
• pp, standing for "pianissimo", and meaning "very soft".

ppp  → m →   fff

Crescendo and Decrescendo