Off-chain refers to transactions, data storage, or computations that occur outside of the main blockchain. Off-chain solutions are used to improve scalability, reduce costs, and increase transaction speed.
Off-Chain Solutions
Layer 2 Networks: Process transactions off the main chain and periodically settle results on-chain (Lightning Network, Arbitrum).
State Channels: Direct off-chain transaction channels between parties.
Off-Chain Storage: Large data (images, documents) stored on systems like IPFS, with only a hash reference stored on-chain.
Off-Chain Computation: Complex calculations performed off-chain with results submitted to the blockchain.
Tradeoffs
Off-chain solutions sacrifice some of the blockchain's trustless, transparent properties in exchange for speed and cost efficiency. The security of off-chain transactions depends on the specific mechanism used to eventually settle or verify them on the main chain.