Glossary / Lightning & layer 2
Lightning address
- Definition
- A Lightning address looks like an email address, user at domain, and resolves to a web endpoint on that domain which hands your wallet a fresh Lightning invoice on request.
Nobody wants to read out a hundred character invoice. A Lightning address replaces it with something you can say on a podcast, and it works because the address is not a payment request at all, only a pointer to a server that mints them. The specification is one page long, LUD-16, and the whole flow is one HTTPS request.
How it works
A Lightning address is a rewrite rule from an email-shaped string to a URL.
Given satoshi@example.com, a wallet builds the URL https://example.com/.well-known/lnurlp/satoshi and sends a GET request. The server answers with the standard LNURL-pay JSON: a callback URL, a minimum and maximum it will accept in millisatoshis, and a metadata block describing the recipient. The wallet shows you that description, you enter an amount, and it calls the callback with your amount. Back comes a BOLT11 invoice for exactly that sum, which the wallet checks and pays.
The username portion is restricted to lowercase letters, digits, hyphens, underscores and periods, with an optional plus sign for services that support tags in the style of user+label@domain. A bare @example.com is allowed as a default identity and resolves to the reserved username underscore. Onion domains use plain HTTP, since Tor already provides the transport security that TLS would.
That is the entire specification. There is no new cryptography, no new message type, no change to any node. A Lightning address is a naming convention layered on LNURL-pay, which is itself layered on a normal invoice, and each layer can be removed without breaking the one below it.
Where you see it
Lightning addresses are how most people publish a way to be paid.
Custodial wallets and Lightning-native apps hand one out at signup, because the provider already runs the web server and the node the address needs. Podcast feeds carry them for streaming payments. Social profiles, tip jars and conference badges use them for the same reason a business card carries an email address rather than a bank wire template.
Running your own takes a domain and a small service that answers the well-known path, which is more work than it sounds until you have somewhere reliable to host it. This is why the overwhelming majority of Lightning addresses in circulation belong to a service provider, and it is the part worth thinking about before you print yours on something.
Two practical limits follow from that. First, whoever operates the domain sees every request for an invoice, including the amounts and the timing, so an address is a privacy trade even when the wallet behind it is not custodial. Second, an address only works while the domain works. If the provider shuts down, changes its terms, or loses the domain, every place you published the address now points at nothing. Treat it as a convenience layer, not an identity you own, unless the domain is one you control.
Lightning address vs Bitcoin address
A Lightning address is a lookup key on the web; a bitcoin address is a spending condition on the blockchain. Send on-chain bitcoin to satoshi@example.com and nothing happens, because there is no such thing as an on-chain transaction to a domain name. Send Lightning to bc1q followed by 38 characters and nothing happens either. They look superficially similar in a wallet's "send" field and share no machinery at all: one triggers an HTTPS request, the other encodes a script that miners will enforce. A bitcoin address works forever and needs no server; a Lightning address needs a live server and stops working the day that server does.