What is a service, and when will you use it?

Angular services are singleton objects which get instantiated only once during the lifetime of an application. They contain methods that maintain data throughout the life of an application, i.e. data does not get refreshed and is available all the time. The main objective of a service is to organize and share business logic, models, or data and functions with different components of an Angular application.

The separation of concerns is the main reason why Angular services came into existence. An Angular service is a stateless object and provides some very useful functions.