Services are the major workhorses in the AngularJS environment. Services are singleton objects that provide functionality for a web app. For example, a common task of web applications it to perform AJAX requests to a webserver. AngularJS provides an HTTP service that houses all the functionality to access a webserver.
The service functionality is completely independent of context or state, so it can be easily consumed from the components of an application. AngularJS provides a lot of built-in service components for basic uses, such as HTTP requests, logging, parsing, animation, etc. You can also create your own services and reuse them throughout your code.