Each bean created by a Spring container has a default Singleton scope; Spring treats it as one instance of the bean, and it is served for each request for that bean from the cache inside the container. In dependency injection, a bean defined as a singleton is injected as a shared bean from the cache. 

A Singleton bean scope is restricted to the Spring container, compared to this Singleton pattern in Java, where only one instance of a specific class will ever be created per ClassLoader. This scope is useful in web applications as well as standalone applications, and stateless beans can also utilize a Singleton scope.

On the off chance that three beans have distinctive IDs but the same class with a Singleton scope, at that point, three instances will be made of that class and in terms of bean ID, as only one instance of the singleton bean is made: