Why a Windows Service?
One of the most common requirements of some businesses is long-running scheduled jobs based on some time interval. For example: sending a newsletter everyday afternoon or send an email alert to the customer for every one hour.
So building a Windows Service could be one of the reliable solutions to do the goal that can do the required job in the behind the scenes without interfering others users on the same computer.
it is copy from below link,
please refer for more details
http://www.c-sharpcorner.com/UploadFile/naresh.avari/develop-and-install-a-windows-service-in-C-Sharp/
