Unconfirmed Transaction
mempool · fees
A transaction seen by the network but not yet included in a block, so its confirmation count is zero.
An unconfirmed transaction is pending in one or more node mempools. It has been broadcast, but miners or validators have not yet included it in a block accepted by the network.
Confirmation reliability depends on fees, mempool policy, conflicts, and network rules such as RBF. Users may be able to raise the fee, use CPFP, rebroadcast, or wait for congestion to clear.
Related terms
Mempool
→A node's local set of unconfirmed transactions accepted for possible relay and block inclusion.
blockchain · node
Replace By Fee (RBF)
→A mempool policy that can accept a conflicting unconfirmed transaction when the replacement satisfies fee and relay rules.
bitcoin · policy · fees
Zero Confirmation
→A transaction observed before any block has included it.
transaction · security
Confirmations
→The count of blocks confirming a transaction, usually including the block that first contains it.
security · blockchain