An API call is a request made by a software application to a server, asking for specific data or services. The term "API" stands for Application Programming Interface, which is a set of rules that allows different software programs to communicate with each other. When an application makes an API call, it sends a request to the server, which processes the request and returns the appropriate response. API calls are essential for enabling functionalities in applications, such as retrieving data from a database or interacting with external services like social media platforms. They help developers integrate various features without needing to build everything from scratch, making software development more efficient and streamlined.