What is a sat?
A sat (or satoshi) is the smallest piece of a bitcoin. A whole bitcoin is a lot: it is split into 100,000,000 pieces, and those pieces are what people pay with. So one sat is worth 0.00000001 bitcoin, and it is the smallest grain there is.
And Lightning?
On the main chain, a payment is a permanent record: you wait your turn and pay fees that become absurd for 100 sats. Lightning is a protocol built on top of bitcoin that fixes this: two people open a channel, exchange as many payments as they like off the chain, and only settle the balance at the end. The result: one second, almost nothing — and they are still the same sats.
Getting sats, in three steps
Buy bitcoin
On a platform, in euros, pounds or dollars. Check that it is authorised in your country.
Send it to your wallet
A withdrawal to your Lightning wallet: from then on, the sats are yours, not the platform's.
You're ready
You pay by scanning a QR code or using a name@domain address: settled in a second.
Where to buy
- Krakensupports Lightning withdrawals
- Strikebuilt for Lightning, recurring buys
- Coinbasevery broad, Lightning by invoice
- Bitpandasimple, licensed in the EU
- Bitstamplong-standing platform, market-oriented
- Relaibitcoin only, regular savings
In France there are also Coinhouse, Bitstack and Paymium. The country-by-country details, with the official registers, are further down.
Lightning wallets
- Phoenixself-custodial the simplest, automatic channels
- Blinkcustodial fixed address, ideal to start
- Zeusself-custodial reusable address, to go further
- Albyself-custodial your own node, a
name@domainaddress - Aquaself-custodial @aqua.net address, no settings
- Wallet of Satoshicustodial very simple, but the service holds the keys
A self-custodial wallet leaves you the keys: write the recovery phrase down on paper. A custodial wallet is simpler, but a third party holds your sats.
Learn more
About bitcoin
- bitcoin.org
the historic community site: getting started, wallets, common questions. - The 2008 white paper
Satoshi Nakamoto's nine pages, the original source. - Bitcoin Optech
the reference technical newsletter, to understand the inner workings of the network.
About Lightning
- lightning.network
the protocol's overview: channels, routing, settlement. - The BOLT specifications
the documents that define Lightning, on GitHub. - LNURL (LUDs)
what lies behind aname@domainaddress or a QR code.
These links point to community or technical sources, never to a site that sells something. Beware of lookalikes: a site with "bitcoin" in its name that pushes you towards other cryptocurrencies or towards an "investment" is not a source of information — bitcoin.org and bitcoinops.org are.
Depending on where you live
Authorised platforms, available wallets and taxation change from one country to another — sometimes from one state to another. Six pages, each with its official sources (in French for now):
France
MiCA-authorised providers (AMF white list), flat tax.
European Union
MiCA licences, the European passport, taxation by country.
United Kingdom
FCA registration, the financial promotions regime, capital gains tax.
United States
Federal and state registration, the case of New York.
Japan
Exchanges registered with the FSA, gains taxed as income.
China
Ban on crypto services: what the law says.
Quick questions
How many sats in a bitcoin?
100,000,000. One sat is worth 0.00000001 bitcoin, and it is the smallest possible unit on the main chain.
Do I need an account to pay with Lightning?
No: a wallet is enough. No e-mail, no bank card, no ID — the payment goes from one wallet to another.
How much does a Lightning payment cost?
A few sats at most, often less than one sat. A payment on the main chain, on the other hand, costs several thousand sats when the network is busy.