1. ~ invert the case of the character under the cursor (i.e. lowercase becomes UPPERCASE and vice versa) g~ followed by motion inverts the case of those characters for example: g~e, g~$, g~iw, etc
2. gu followed by motion changes those characters to lowercase for example: gue, gu$, guiw, etc
3. gU followed by motion changes those characters to UPPERCASE for example: gUe, gU$, gUiw, etc