Multi-Signature (Multisig)
Plain English
A wallet that requires multiple people to approve a transaction, like a safe deposit box that needs two keys to open. For example, a "2-of-3 multisig" means any 2 out of 3 designated people must approve. Great for organizations or securing large amounts.
Technical
A cryptographic scheme requiring M-of-N signatures to authorize transactions. Smart contracts enforce that a threshold number of designated signers must cryptographically approve before execution. Eliminates single points of failure. Used for treasury management, organizational wallets, and enhanced security. Solana implements multisig through Squads Protocol and SPL programs.