An API Call is a request that a program sends to an API (Application Programming Interface) to use specific data or functions provided by another software or service. APIs enable communication between different software applications by defining standardized requests and responses.

API Calls typically consist of a URL, an HTTP method call such as GET, POST, PUT, or DELETE, headers, and possibly a body with additional data. The HTTP method determines the type of request: GET is used to retrieve data, POST to send data for creation, PUT to update existing data, and DELETE to remove data.

API Calls offer benefits such as modularity, allowing systems to be developed and maintained independently, and reusability, as the same APIs can be used by different applications. Security aspects are also crucial: API Calls should be designed securely by using authentication methods like OAuth and encryption like HTTPS to prevent unauthorized access.