What is a mempool?
A mempool (short for "memory pool") is the queue of pending and unconfirmed transactions for a Bitcoin node. There is no one global mempool: every node on the network maintains its own mempool, so different nodes may hold different transactions in their mempools.
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“Cypherpunks write code. … We know that software can’t be destroyed, and that a widely dispersed system can’t be shut down.”
-A Cypherpunk’s Manifesto by Eric Hughes