API keys are a crucial component of securing Application Programming Interfaces (APIs), providing a unique identifier for authentication and controlling access to API resources. By including an API key in URL parameters or request headers, developers can restrict what the key can access, enhancing app security. API keys can be obtained through the API provider's settings section, where users can document their use and specify restrictions, such as Space ID. While not as secure as authentication tokens like OAuth, API keys can be combined with other methods to provide robust security measures. Understanding how to utilize API keys effectively is essential for building reliable digital experiences that power various tech applications.