Alamofire is a Swift-based networking library that simplifies the process of making HTTP requests in iOS apps. It provides an easy-to-use interface for handling data tasks, such as downloading JSON or image files, uploading data, and working with authentication challenges. It supports various protocols, like HTTP, SPDY, and HTTP/2, and can handle cookies, authentication, and caching. Alamofire is a popular choice among iOS developers for building networked iOS apps.