A non-custodial profile in Surf is a smart contract which is used to buy, store, receive and send Evers.
Each profile supports multisig and can update the smart contract code to fix bugs and add features.
When you create a new Surf profile, its address and seed phrase are automatically generated. Knowing this address, anyone can send you Evers. If you too want to send Evers, you need to activate your profile first.
Please note that your profile balance should never hit zero. Otherwise, the profile will be frozen and you'll need to go through a complicated procedure to restore it.
The Surf profile smart contract has been formally verified. This means its work and reliability are not just tested but proved mathematically.
The source code of the Surf profile is partly available on GitHub.