MPC wallets and crypto custody are the systems that hold the secret keys to crypto for companies and institutions, so that no single person can move the money. MPC stands for multi-party computation. Custody means holding an asset safely on behalf of its owner, as a bank vault holds gold.
Here is why custody matters. On a blockchain, whoever holds the private key can move the money. A private key is a long secret number, much like a password that can never be reset. If an employee copies it, the money can be stolen. If it is lost, the money is lost for ever. So a company that holds crypto worth crores cannot let one laptop or one person hold the full key.
An MPC wallet solves this by never creating the full key in one place. Instead, the key exists as several separate pieces, called key shares. Each share is held by a different party, for example the company's treasury team, its security team and the custody provider. To approve a payment, a set number of parties must take part, for example any two out of three. Each party does a calculation with its own share. The calculations together produce a valid signature, but no party ever sees the other shares, and the full key is never put together.
Consider a crypto fund in Mumbai that wants to move 10 Bitcoin to a crypto exchange in order to sell them. A fund manager requests the transfer in the custody dashboard. A risk officer approves it from a separate device. The custodian's server adds the third share's calculation only if the transfer meets the fund's rules, such as a daily limit. Only then is the transaction signed and sent to the blockchain.
This is the security idea of least privilege applied to money: each person can do only part of the job. The shares themselves are protected with encryption and with encryption key management, often inside special tamper-proof hardware.
The older approach is called multisig, short for multi-signature. In multisig, there are several complete keys, and the blockchain itself checks that enough of them have signed. In MPC, there is one key, split into shares, and the blockchain sees only one ordinary signature. Custody providers sell this service to exchanges, to crypto wallet infrastructure companies and to tokenisation platforms.