Multi-signing

Multi-signing lets an account demand several signatures before a transaction counts. A regular key can be a spare key that signs for the account while the master key stays offline.

One key on a phone is one mistake, one theft, or one lost device away from an empty account. Shared control is how a family or a company avoids that single point.

You put a signer list on the account. Each signer has a weight, and the list has a quorum. A transaction is valid only when the weights of the signatures reach the quorum. Three people with weight 1 and a quorum of 2 means any two can move funds, and one cannot.

A regular key is simpler. It is one extra key allowed to sign instead of the master. You can keep the master key in a drawer and use the regular key day to day. If the regular key is stolen, you still have the master key to replace it, as long as you stored the master key well.

Real example: the XRP Ledger supports both. Signer lists and regular keys are account settings, changed by signed transactions, not by emailing a support desk. Source: Multi-Signing.