Vim Visual Mode

v # character-wise visual mode
V # line-wise visual mode
Ctrl + v # block-wise visual mode

o # move to other end of selection
aw # select a word
ab # select a block with ()
aB # select a block with {}
ib # select inner block with ()

y # yank selected text
d # delete selected text
c # change selected text
> # indent right
< # indent left
~ # swap case
u # convert to lowercase
U # convert to uppercase

ggVG # select all text in file