Angular services are substitutable objects that are wired together using dependency injection (DI). You can use services to organize and share code across your app. We will discuss the ways in which we create our own services and the benefits and differences between each of them.
AngularJS: Best Practices using the scope
When building any Angular app, any performance optimization boils down to: Minimizing the number of binding expressions and hence watches, Making sure that binding expression evaluation is quick and Optimizing the number of digest cycles that take place.
Services are objects whose API is defined by the developer writing the service. Specialized objects conform to a specific Angular framework API. These objects are one of controllers, directives, filters or animations.