API is an acronym that stands for Application Programming Interface. An API is a set of protocols, tools, and definitions that allow software programs to interact with each other and share data and functionality. APIs are an essential part of modern software development, and are used to enable applications to communicate and exchange data with other applications, services, and devices over the internet or other networks. APIs typically provide a set of defined functions and interfaces that can be called by a client application, and provide a consistent and predictable way for the application to access and use the functionality and data provided by the API. APIs are commonly used in web development, mobile development, and other contexts where different applications need to be able to interoperate and exchange data.