What does this sign mean?

[nonfox]

Hi...
I've just downloaded Bach - Minuet in G, BWV 114 (The one at the frontpage).
Above some of the notes is a little sign, a kind of wave. It almost lokks like this: ~
What does this sign mean?

[pianistimo]

it's called a mordent.  upper auxillery note, primary note, under auxillery note,  primary note.  music dict. probably explains it better.

[cfortunato]

At that sign, you don't play a C, but D-C-B-C very rapidly, pretty much on the beat.

[tac-tics]

https://www.iment.com/maida/familytree/henry/music/bachnotation.htm