The final thing we see in a contract is at the bottom of it—the signatures! In many ways, signatures are the most important part of a contract because they represent the fact that all counter-parties have agreed to the information contained within it. And of course, we see lots of signatures in the real world. Daisy's shop receipt normally has her signature on it—either physical or digital, via a private key. In simple transactions, the store's signature is actually implicit—they put a transaction code on a branded receipt, and keep a copy for their purposes—this satisfies the purposes of a signature.

However, for higher-consequence transactions, all counter-parties will be required to explicitly sign a contract. Even more pointedly, to ensure that every party is entering the contract with their eyes open, an independent third-party such as a solicitor, notary, or regulator, may be required to sign the contract to verify the willing, and free, participation of those counter-parties explicitly involved in the transaction.