Services (zz from MSDN)

Services

A service application conforms to the interface rules of the Service Control Manager (SCM). It can be started automatically at system boot, by a user through the Services control panel applet, or by an application that uses the service functions. Services can execute even when no user is logged on to the system.

A driver service conforms to the device driver protocols. It is similar to a service application, but it does not interact with the SCM. For simplicity, the term service refers to a service application in this overview.