Using the Vault CLI, what command is used to authenticate to Vault?

`vault auth` is not a valid top-level command for client authentication; it's typically used with subcommands like `vault auth enable` for managing auth methods.

The `vault login` command is the designated CLI command to authenticate a user or application to Vault, often requiring parameters specific to the chosen authentication method like `userpass` or `token`.

`vault user` is not a valid Vault CLI command; user management is typically handled through specific auth method paths, e.g., `vault write auth/userpass/users/myuser`.

`vault creds` is not a valid Vault CLI command for client authentication; 'creds' might be part of a path for a secrets engine like `database/creds`.