An API credential is a set of sensitive information, such as an API key, token, or client secret, used to authenticate and authorize access to an application programming interface (API). API credentials verify the identity of the user, application, or system requesting access, ensuring only authorized parties can interact with the API. Proper management and protection of API credentials are critical to prevent unauthorized access, data breaches, or misuse of services. Credentials should never be exposed in public repositories or client-side code, and should be rotated regularly to maintain security. Compromised API credentials can lead to significant security risks.