Web APIs (Application Programming Interfaces) serve as a bridge connecting different applications, enabling them to communicate and share data. They provide a standardized way for systems to interact, allowing developers to access features and functionalities of other services without having to understand their internal workings. APIs can facilitate various tasks, such as integrating payment gateways, retrieving live data, or enabling user authentication across platforms. By simplifying these processes and fostering interoperability, web APIs play a crucial role in developing modern software applications and enhancing user experiences.