vim is a modal editor. This means that at any time inside a vim session, the user is going to be in one of the modes of operation. Each one of offers a different set commands, operations, key bindings...

Normal mode (or Command mode)

• The mode vim starts in.
• From other modes, usually accessible by Esc.
• Has most of the navigation and text manipulation commands.

See :help normal-mode.

Insert mode

• Commonly accessed by: a, i, A, I, c, s.
• For inserting text.

See :help insert-mode.

Visual mode

• Commonly accessed by: v (characterwise), V (linewise), <C-v> (blockwise).
• Basically, for text selection; most normal commands are available, plus extra ones to act on the selected text.

See :help visual-mode.

Select mode

• Accessible from insert mode with <C-g>.
• Similar to visual mode but with a lot less available commands.
• Contrary to insert mode, it is possible to type right away.
• Rarely used.

See :help select-mode.

Replace mode

• Accessible from normal mode with R.
• Allows to overwrite existing text.

See :help replace-mode.

Command-line mode

See :help command-line-mode.

Ex mode

See :help Ex-mode.