mempool
The waiting area where unconfirmed cryptocurrency transactions sit before being added to the blockchain.
A mempool (memory pool) is a temporary storage space that holds pending transactions waiting to be processed and added to a blockchain. When someone sends cryptocurrency, their transaction doesn’t instantly become permanent—it first enters the mempool, where it waits for miners or validators to include it in the next block. Think of it like a post office sorting facility where mail waits to be processed.
The mempool exists because blockchains process transactions in batches (blocks) at regular intervals, not instantly. When you see headlines about transaction congestion or high fees, the mempool is often involved—a full mempool with many waiting transactions can mean slower processing and higher costs to jump the queue. For news readers, a crowded mempool typically signals network congestion, while an empty one suggests smooth operations.
Written once as a plain-English reference, not as advice. Nothing here is a recommendation to buy or sell anything.