Replace-By-Fee (RBF) is a mechanism by which a transaction still pending confirmation can be replaced by another transaction, spending the same input(s) (or some of them) and paying a higher transaction fee. This allows Bitcoin users to increase the fee attached to a transaction even after they broadcast it, for example in an attempt to accelerate its inclusion into a block by nudging miners to add it to their block candidate.

Ressources

• Bitcoin Optech