A windows service is an application which when installed on 
a system, appears in the services console window 
(services.msc). It is different from a standard exe in the 
sense that we define/configure a time interval at which 
this application would run on a regular basis. So this time 
interval is taken care of by the Windows and it executes 
that application at regular intervals. Whereas in a 
standard exe is would not be the case. One has to click on 
that exe each time he wishes to execute that application.