An ethereum wallet can be thought of as a digital key manager for the private keys needed to move ether (ETH) on the ethereum blockchain.
Some ethereum wallets allow one to interact with ethereum smart contracts and store tokens.
Casa vaults are multsignature wallets / key managers that creates a multisig smart contract for users of the Casa app. The smart contract creates a contract address multiple keys, a smaller subset of which are required to sign a transaction (e.g., a "2-of-3" wallet, or a "3-of-5" wallet).
Wallets that require multiple signatures to spend are considered more secure than single-signature wallets, which only require one key signature to move funds. Single-signature wallets also centralize more risk into the one existing key.
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