How do I re-insert the exact same text I typed during my last insert mode session?

Explanation

Pressing <C-a> while in insert mode inserts the same text that was typed during the previous insert mode session. Vim stores the last inserted text in the dot register (.), and <C-a> replays it directly — no need to escape, use ., and re-enter insert mode. This is particularly useful when you need the same literal text repeated in multiple non-adjacent locations within a single insert session or across successive inserts.

How it works

• <C-a> — in insert mode, replays the contents of the . register (last inserted text) at the current cursor position
• <C-@> — identical to <C-a>, but also exits insert mode and returns to normal mode afterward (like i<C-a><Esc> in one keystroke)
• The dot register holds what you typed since entering insert mode last time, including backspaces and special characters

Example

You are in insert mode and have just added a repeated pattern at the end of one line. You move to the next line (using <C-o>j to stay in a single insert session) and want to add the same text:

const FOO_TIMEOUT = 5000;  ← just typed FOO_TIMEOUT
const BAR_TIMEOUT = 5000;  ← cursor here

Instead of typing 5000 again, press <C-a> to insert the last typed text.

Tips

• <C-r>. also inserts the last inserted text (via register name), but <C-a> is faster as a two-key chord
• Use <C-@> when you want to replay and immediately return to normal mode
• The dot register is also accessible via <C-r>. in command-line mode for Ex commands
• <C-a> only replays text — it does not replay cursor movements or ex commands