Mempool

A mempool (short for memory pool) is a temporary storage area where pending transactions are held before they are included in a block and confirmed on the blockchain. When a user initiates a transaction, it is broadcast to the network and first goes into the mempool of participating nodes.

Here’s how a mempool works:

1. Pending Transactions: Transactions wait in the mempool until miners (in proof-of-work systems) or validators (in proof-of-stake systems) select and add them to a new block.
2. Transaction Prioritization: Miners often prioritize transactions with higher fees, which means transactions with lower fees may stay in the mempool longer until they are included in a block.
3. Decentralized Storage: The mempool is decentralized, meaning each node in the network maintains its own version of the mempool. While there can be differences in the contents of mempools between nodes, they generally sync up over time as new blocks are added.
4. Clearing the Mempool: Once a transaction is confirmed in a block, it is removed from the mempool. During times of network congestion, the mempool can become large as more transactions are waiting for confirmation.

In essence, the mempool acts as a “waiting room” for transactions before they are finalized on the blockchain.