Modes

KeyMode
i / a / AInsert / append / end-of-line insert
v / V / Ctrl-vVisual char / line / block
:Command-line
RReplace mode
EscBack to Normal

Motions (sample)

MotionMoves to
w / b / eNext word / back word / end of word
0 / ^ / $Start of line / first non-blank / end
gg / GFirst / last line of buffer
f{char} / t{char}Find / till on line
%Matching bracket

Operators

OpAction
dDelete (= cut)
cChange (delete + insert)
yYank (copy)
gu / gULowercase / uppercase
> / <Indent / dedent

Compose: ci" change inside quotes, dap delete a paragraph, gg=G reindent entire file.

Search & substitute

/pattern\c          " case-insensitive search
:%s/old/new/gc      " global replace with confirm
:noh                " clear search highlight