Definition
Memory Pool. A holding area on each network node where unconfirmed transactions wait to be picked up by miners or validators and included in the next block. Higher-fee transactions are generally prioritized.
Why It Matters
Understanding the mempool explains why transactions sometimes take a long time to confirm — especially during periods of high network demand. It also shows why higher gas fees get faster processing.
Example
During the 2021 NFT boom, Ethereum's mempool became congested with thousands of pending transactions. Users had to pay high gas fees to get their transactions included quickly.
Related Terms
Gas Fee
Block
Mining
Node