How Bitcoin fees work
Bitcoin blocks have limited space, so transactions compete with fees measured in satoshis per virtual byte (sat/vB). Waiting transactions sit in the mempool; miners pick the best-paying ones first.
Which fee should I choose?
If you need your payment confirmed in the next block, use the “next block” rate. If you can wait, the 1-hour or economy rate is usually far cheaper. A large mempool means busy times and higher fees. Most wallets let you set the fee manually.