Glossary.
The vocabulary of machine-native commerce — x402 payments, on-chain token safety, and AI-agent discovery — defined plainly, for people and for the models that cite them.
§ x402 & payments
x402 & payments.
- x402
- An open protocol that lets software pay for things over HTTP using the 402 status code. A server answers an unpaid request with payment terms; the client pays in USDC and retries. No accounts, no API keys — the wallet is the identity. → guide
- HTTP 402
- The "Payment Required" HTTP status code, reserved since the 1990s but left unstandardized for decades. x402 gives it a concrete meaning: a 402 response carries the price, asset, recipient, and network, so a client knows exactly how to pay and retry.
- EIP-3009
- An Ethereum standard ("transferWithAuthorization") for gasless token transfers. The payer signs a transfer authorization off-chain and a third party submits it and pays the gas. x402 uses it so an agent can pay in USDC without holding native gas.
- Facilitator
- A service that verifies and settles x402 payments on behalf of a resource server, so the server never touches the blockchain. It checks the signed payment is valid and submits the on-chain settlement.
- Settlement
- The on-chain finalization of a payment — when the signed authorization is submitted and the USDC actually moves. In x402 it happens asynchronously, after the response is sent, so it never slows the API.
- USDC
- A fully-reserved US-dollar stablecoin issued by Circle. It is the default settlement asset for x402 payments, valued 1:1 with the dollar.
- Stablecoin
- A crypto token pegged to a stable value, usually the US dollar (e.g. USDC). Used in x402 so prices and payments are denominated in dollars rather than a volatile asset.
- Base
- An Ethereum layer-2 network incubated by Coinbase, with low fees and fast finality. It is the primary chain for x402 payments and for true402's on-chain safety checks.
§ Token safety & DeFi
Token safety & DeFi.
- Honeypot
- A token you can buy but not sell. The contract, or its hidden logic, blocks or reverts sells, trapping buyers. Static contract scans often miss it; a buy/sell simulation catches it. → guide
- Honeypot simulation
- A check that runs a real buy then sell of a token inside a gas-free eth_call (no actual transaction) to prove it can be sold. It catches runtime sell-blocks that reading the contract cannot. → guide
- Rug pull
- When a token's creators drain its value — removing liquidity, minting and dumping, or flipping a kill switch — leaving holders unable to sell at any real price. → guide
- Liquidity pool
- A smart contract holding a pair of tokens (e.g. a new token plus WETH) that a DEX trades against. Its depth determines how much you can buy or sell without moving the price.
- Liquidity pull
- Removing the tokens backing a pool, collapsing a token's tradeable value to near zero — the most common rug mechanic, and an early warning when it hits a fresh launch.
- Token approval
- An ERC-20 permission letting a contract spend your tokens (an "allowance"). Scams abuse over-broad, unlimited approvals to drain wallets later — revoke ones you do not need. → guide
- Wallet drainer
- Malicious code that, via a deceptive approval or signature (such as a Permit), gains permission to move a victim's tokens and empties the wallet. → guide
- Renounced ownership
- When a token's owner address is set to zero, permanently giving up admin powers like mint, blacklist, and fee changes. A common — though not absolute — safety signal.
- Mint function
- Contract code letting the owner create new tokens at will. If active, the supply can be inflated and dumped on holders — a key risk flag.
- Proxy contract
- An upgradeable contract whose logic lives in a separate implementation that can be swapped after deployment. A token that looks clean today can have its behavior changed later. → guide
- Sniper bot
- Software that buys a token in the first seconds of its launch, before the price moves. Profitable only with fast execution and a pre-trade safety check to skip the scams. → guide
- Whale
- A wallet holding or trading an outsized amount of a token. Following whale buys and sells is a common signal — and large holders can move price on their own. → guide
- DEX
- A decentralized exchange — a smart-contract marketplace (e.g. Uniswap, Aerodrome) where tokens trade against liquidity pools, with no account or custodian.
§ Agents, discovery & GEO
Agents, discovery & GEO.
- AI agent
- Autonomous software that pursues a goal by calling tools and services on its own. Agents cannot fill signup forms or manage API keys, which is why pay-per-call rails like x402 fit them.
New to this? Start with what is x402, try a real check at /check, or read the full guides.