The importaddress command enables the addition of a Bitcoin address or script (in hexadecimal format) to the wallet, allowing it to be monitored as if it were part of the wallet. However, the imported address cannot be used to spend funds. A new wallet backup is required after importing an address.

How is this used?

This command is useful for monitoring external addresses or scripts within the wallet, providing visibility into their transactions and balances without having control over the funds. It is commonly used for tracking cold storage addresses, exchanges, or other external services.