Introduction to the XRP Ledger

Start here

This primer gives everyone the same footing before the advanced material. If you already build on XRPL, skim it as a refresher. If you are new, read it closely and ask questions in the main room; none of it assumes prior XRPL experience.

What the XRP Ledger is

The XRP Ledger (XRPL) is a public blockchain with no central operator. There is no mining. Instead, a network of independent validators agrees on a fresh version of the shared ledger every 3 to 5 seconds. Each agreed version is a validated ledger, and whatever it records is final. You reach the ledger by connecting to a public server over WebSocket.

Throughout the course we use Testnet: a free copy of the network with worthless test money that you request from a faucet. Keep real Mainnet accounts and seeds out of the workshop entirely.

Accounts, XRP, and reserves

An account has an address that starts with r (say, rHb9...). Its secret seed starts with s, signs transactions, and must stay private. XRP is the ledger's native asset; its smallest unit is a drop, and 1 XRP is 1,000,000 drops. You always write an XRP amount as a whole number of drops in a string.

Each account also keeps a small amount of XRP locked as a reserve. It works as an anti-spam deposit rather than a fee, and it rises a little for every object the account owns, such as a trust line or an open offer.

XRP versus issued tokens

Value on XRPL comes in two shapes:

• XRP, the native asset, written as a drops string like "1000000".
• Issued tokens (IOUs), written as an object with a currency, an issuer, and a decimal value — for example { "currency": "USD", "issuer": "rIssuer...", "value": "10" }.

An issued token means nothing without its issuer. Two issuers can both use the code USD, and each is a separate asset. Before an account can hold a token, it opens a trust line to the issuer — in effect saying "I will hold up to this much of this issuer's token." You set one up in the first coding lab.

The transaction lifecycle

Everything on XRPL follows the steps you practised in the readiness check:

1. Build a transaction object that says what you want to happen.
2. Autofill the routine fields (fee, sequence, LastLedgerSequence).
3. Sign it locally with your seed, which never leaves your machine.
4. Submit the signed transaction to a server.
5. Validate: wait for it to appear in a validated ledger, then read the result.

A transaction counts only once a validated ledger contains it. Anything before that, including a cheerful response from submit, is provisional.

Where the DEX and AMMs fit

Trading is built into the protocol, so XRPL has its own decentralized exchange (DEX) with no third-party service in the middle. Liquidity comes from two places that sit side by side:

• An order book, where people post offers to buy or sell at prices they choose.
• Automated Market Makers (AMMs), pools of two assets that quote a price from a formula.

The next two days are about driving both from code. For now, it is enough to know they exist and that the ledger can route a single trade through one or the other, or both.