Fee rate (sat/vB)

The mempool is the waiting room for Bitcoin payments: transactions sent but not yet in a block. Miners usually pick the ones paying the highest fee per byte first.

A block is a batch of Bitcoin transactions added to the chain about every ten minutes. The miner who finds it collects the new coins and the fees.

Bitcoin has no account balances. Your wallet holds separate “coins” called UTXOs, like notes in a purse; a payment spends some of them and creates new ones, including change back to you.

SegWit was a 2017 upgrade that moved signatures into a separate part of the transaction. It fixed a long-standing bug, made room for more transactions and opened the door to the Lightning Network.