Definition
Refers to any transaction, data, or activity that is recorded directly on the blockchain. On-chain actions are public, permanent, and verifiable by anyone.
Why It Matters
Knowing whether something is on-chain or off-chain tells you about its transparency, security, and permanence. On-chain data is the gold standard for verification.
Example
Swapping ETH for USDC on Uniswap is an on-chain transaction — it creates a permanent public record on the Ethereum blockchain.
Related Terms
Blockchain
Block Explorer
Layer 2
Smart Contract