A service is an entity that can perform a work . It's a kind of global task. A service is global to your application. A service provides good Maintenance and factorization of code
This container manage two differents entities the services and the parameters. This container allows us to retrieve services and parameters to any level of codes. This one allows us to use the design pattern of dependency injections.
Nodefony can manage all services by injection .
During startup , autoloader load services and read config file services.xml in bundle.
This Part look in container global to find services to inject and register new service in the container.
The injection service is completely linked with the kernel service container