2.19 Invoices, Keysend & Lightning Addresses

There are three common ways to pay or get paid on Lightning, from oldest to most user-friendly:

1) Invoices. The classic style: the person being paid generates a one-time invoice (a long string starting with 'lnbc...') for a specific amount, often shown as a QR code. The sender scans, taps confirm, done. Each invoice is single-use, like a unique payment link.

2) Keysend. A way to push a payment to someone without asking them for an invoice first. Great for tipping or 'streaming' tiny payments (a few sats per minute of a podcast).

3) Lightning Addresses. The friendliest format — they look like email: alice@walletname.com. Behind the scenes the wallet automatically requests a fresh invoice when you pay. You'll see these on creator bios, tip jars, and Nostr profiles everywhere.

Pro tip: most modern Lightning wallets support all three, and they're interoperable across wallets. You don't have to use the same app as the person you're paying.