Mempool
The waiting room where broadcast transactions sit before a miner or validator picks them for a block.
When you send a transaction, it doesn't land on the chain instantly. It first enters the mempool, a holding area of unconfirmed transactions that each node keeps. Block producers pull from here, usually favoring the higher fees.
When the mempool swells, fees spike and confirmations slow, because everyone is bidding for limited block space. Watching mempool size is a quick read on how congested a network is right now.
Related terms
A signed instruction that moves value or data on a blockchain, recorded permanently once miners or validators confirm it.
Transaction FeePaid to the network for processing a transfer, this charge rises and falls with how busy the chain is.
ConfirmationEach new block added on top of the one holding your transaction, deepening it and making reversal far harder.
BlockA batch of transactions bundled together, time-stamped, and cryptographically linked to the block before it.