Service tags overview
Some services have tags, which are defined in the service definition. Tags are used to define a group of related services, or to specify some aspect of how the service behaves. Typically, if you tag a service, your service class must also implement a corresponding interface. Some common examples:
access_check: Indicates a route access checking service; see the Menu and routing system topic for more information.
cache.bin: Indicates a cache bin service; see the Cache topi