Vim

Enters insert mode before the cursor.

Returns to normal mode from insert, visual, or command mode.

Enters visual mode, for selecting text character by character.

Enters command mode, for ex commands like :w, :q, :s.

Writes (saves) the file.

Quits — fails if there are unsaved changes.

Writes then quits.

Quits and discards unsaved changes. There is no undo once you've quit — confirm you actually want to lose the edits first.

Shorthand for :wq in normal mode.

Left, down, up, right — the original arrow keys, still faster than reaching for real ones.

Jumps to the start of the next word.

Jumps to the start of the previous word.

Jumps to the start of the current line.

Jumps to the end of the current line.

Jumps to the first line of the file.

Jumps to the last line of the file.

Jumps to line 42.

Deletes (cuts) the current line.

Yanks (copies) the current line.

Pastes after the cursor/current line.

Undoes the last change.

Redoes a change that was just undone.

Deletes the character under the cursor.

Deletes from the cursor to the start of the next word.

Deletes the current line and enters insert mode — change the whole line in one step.

Searches forward for a pattern. Press n for the next match, N for the previous.

Searches backward for a pattern.

Replaces every occurrence of old with new on every line in the file.

Same, but prompts for confirmation before each replacement — safer for a change you're not fully sure of.

Character-wise visual selection.

Line-wise visual selection.

Block-wise visual selection, for editing a rectangular column across multiple lines.

Indents the selected lines (in visual mode).

Opens another file in the current window.

Switches to the next open buffer.

Lists all open buffers.

Splits the window horizontally.

Splits the window vertically.