A computer or software instance participating in a blockchain network.
Your wallet connects to a node for balance information; that node can also relay your signed transaction to its peers.
A token with an individual identity rather than interchangeable units, commonly called an NFT.
“I bought the NFT—can I sell prints?” Token ownership alone doesn’t answer that; you check the rights attached to the artwork.
A basic instruction understood by a virtual machine or scripting system.
An EVM trace shows an ADD instruction combining two values, followed by instructions that store the result.
A rollup that accepts submitted execution results subject to a process for challenging invalid results.
A challenger spots an incorrect state update and disputes it while the optimistic rollup's challenge window is still open.
A mechanism that supplies information a blockchain application cannot directly obtain for itself.
"I haven't borrowed more, but my collateral ratio changed after the oracle updated the price of my ETH."
Influencing data an application treats as an authoritative input, such as its collateral price.
The lending app reads a thin pool's price just as an attacker distorts it, giving the collateral a misleading valuation.
A collection of active buy and sell orders arranged by price and matching rules.
You open the book and see bids below the market, asks above it and different quantities at every price level.
Backing a debt or position with collateral worth more than the obligation it supports.
A position has $1,000 of collateral backing $400 of debt; it starts overcollateralized, but falling collateral prices can shrink that buffer.
An additional secret that some wallet recovery schemes combine with recovery words to derive a wallet.
"Same recovery words, different BIP-39 passphrase, different wallet. This is not just changing the app's unlock password."
An ERC-4337 contract that can pay gas costs for eligible smart-account operations.
Your first app transaction has no ETH charge to you because its paymaster covers the gas after checking that the operation qualifies.