These are transactions that take place on the blockchain. These transactions are recorded on the distributed ledger and are accessible to anyone with a copy of the ledger. As a result, every on-chain transaction causes an update to the overall blockchain network.
These transactions should, in theory, take place in real-time. In practice, however, they can take an eternity. The transaction must first be validated by several network participants. Miners must then solve complex mathematical problems in order to group validated transactions into blocks and add them to the blockchain ledger. This procedure can be very time-consuming.

On-chain transactions are digital transactions that are recorded and validated directly on a blockchain network. These transactions involve the transfer of cryptocurrencies or other blockchain-based assets and are processed by miners or validators through consensus mechanisms like Proof of Work (PoW) or Proof of Stake (PoS). Once confirmed, they are permanently added to the blockchain's public ledger, ensuring transparency and immutability. On-chain transactions typically require network fees (gas fees on Ethereum) and may take time to finalise, depending on congestion. Unlike off-chain transactions (which occur outside the main blockchain), on-chain transactions provide full decentralisation, security, and verifiability. They are essential for activities like peer-to-peer crypto transfers, smart contract executions, and decentralised finance (DeFi) operations.