In this track: From send to settlement
What is a mempool?
A node’s local collection of pending transaction candidates.
Each librarian can keep a tray of forms waiting to be processed. The trays need not contain exactly the same forms at the same instant.
Maya prepares an instruction: send 0.01 pretend ETH to Leo.
A local simulation. Nothing is signed or sent to a network.
Many local collections
A mempool is not one global server where every Ethereum transaction waits. Nodes receive and share transaction candidates, and their local collections can differ because of timing, policies and network conditions.
Nodes check before sharing
A node applies validation and admission rules to a candidate. The checks can involve authorization, nonce, fee conditions and available resources. A pool entry is still only a candidate for later inclusion.
Not every path is public gossip
Some transaction flows use private submission paths or other mechanisms. Therefore, not seeing a transaction in one public pending feed does not prove that no proposer or service knows about it.
Watch the model
In the sharing stage above, packets travel from a wallet to Node A and onward to peers. A request enters Node C’s local tray. This picture explains propagation; it does not depict one universal queue or promise a first-in-first-out order.
Is the mempool a single worldwide queue shared identically by every node?
Pending pools are local views with potentially different contents and policies.
Original explanations by EtherTools. Examples are educational and source-linked; this site is independent of the Ethereum Foundation. Our approach.