1.A service application conforms to the interface rules of the Service Control Manager(SCM).
2.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.
3.Services can execute even when no user is logged on the system.
1.一个服务应用程序符合windows服务控制管理器的界面规则。
2.可以在系统启动时自启动，或者由用户通过服务控制面板程序启动，或者由应用程序通过调用service functions来启动。
3.没有用户登录系统时，服务也可以运行。
Service 是一种特殊的Application
link:
http://msdn.microsoft.com/en-us/library/windows/desktop/ms685141%28v=vs.85%29.aspx