Cryptocurrencies do not scale. In this technical deep-dive, we provide an overview of an alternative scaling approach, off-chain protocols, that lets parties transact locally amongst themselves instead of the global network. Off-chain is remarkable as in the best case it lets parties bypass all network fees and blockchain latency, and in the worst-case, the parent blockchainsafeguards the funds of all honest parties. We'll cover the two leading approaches, channel-based networks (lightning et al) and commit-chains (plasma & rollup et al) alongside the new the always online assumption and how the community is trying to alleviate it. If we, as a community, can pull off the implementation of off-chain protocols, it will hopefully unleash a truly permissionless, global and internet-scale financial system.