Aight so mempool's the waitin' room for transactions that ain't been confirmed yet. Every node keeps its own version. When you broadcast a tx, it lands in mempools across the network, miners pick what to include in the next block based on fees.

Cheap days = it gets in fast. Busy days = wait, or bump your fee. That's the whole dance.

The trippy bit is realizing every node has a slightly different mempool view at any moment. There's no canonical one until a block confirms.