What is a multi-sig wallet in cryptocurrencies?

Multi-sig wallet in cryptocurrencies is a concept that stands for multi-signature and means a special kind of digital signature that allows several users to jointly sign documents as a group. A multi-signature is a combination of several unique signatures. The technology of multi-signatures in cryptocurrencies was first applied in 2012 in Bitcoin. This eventually led to the creation of multi-signature wallets. The principle of multi-signature implies that access to the assets on the wallet is possible only if all users simultaneously provide their keys.