What is Off-Chain? Off-chain is not the main blockchain system, but transactions occur outside. Through this, it is possible to solve the scalability problem that could not be solved on-chain. Offchain records only core data on the blockchain, and at this time, data that needs high speed is recorded on the central server of the DApp, not the blockchain. Offchain has advantages such as low fees, high speed, and high transaction throughput. However, there is also a disadvantage, which is that the transaction details recorded in the off-chain cannot be fully trusted. A representative method for solving the off-chain scalability problem is a lighting network. The Bitcoin protocol takes an on-chain payment method that records all transactions generated in the network on the blockchain. This takes a very long time to verify because it stores all the transaction data in the block. Therefore, delays in confirmation occur, and fees paid to miners naturally become expensive. In the end, Bi...