Operator-Pending Mode

The fourth mode you didn't know about.

Keys: d, c, y

Between pressing an operator (d/c/y/...) and pressing the motion, Vim is in operator-pending mode. It's a real mode with its own status ("-- OPERATOR --") and its own mappings.

Vim has four base modes, not three. Between an operator key like d and the motion that completes it, Vim is in operator-pending mode โ€” waiting for a motion or text object.

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See also: The Vim Grammar, The Modes