MPC wallets differ from regular wallets such as single-key, multi-signature wallets. Single-key wallets rely on one private key that can be easily lost or stolen, while multi-signature wallets create separate keys and allow you to sign with a majority to perform a transaction. 

MPC looks to meet in the middle and borrow from both concepts; with MPC, the private key is broken up into shares, encrypted, and divided among multiple parties. Each party will independently compute their part of the private key share they hold to produce a signature without revealing the encryption to the other parties. 

This means there is never a time when the private key is formed in one place; instead, it exists in a fully “liquid” form and is compiled when it is needed.

A simple example would be to use MPC as a hybrid custody model where you would hold one shard, and your wallet provider could hold another shard on their server that is combined on the fly when you need to conduct a transaction. 

In another example, you could have one shard in your hot wallet and another shard on an air-gapped signing device and compile using a QR code or provide a pre-signed signature from your device to be compiled with your MPC wallet.