You can authenticate with Twilio's API using the Account ID as the username and the primary or secondary auth token. If the primary token is compromised, you can promote the secondary token to the primary token which will make the old primary token unusable. You can protect your credentials by segmenting your account with subaccounts. Subaccount authentication ensures that an authenticated user's actions are limited to their own subaccount, preventing a potential security breach if an auth token or API Key for a subaccount is compromised. Twilio now recommends using API Keys instead of Account Credentials, offering greater flexibility and control over access to its services. With API Keys, you can create multiple keys with varying levels of access, making it easier to manage permissions and revoke access when necessary.