IIS stands for Internet Information Services which is also known as a Windows web server. IIS is available to windows servers and is installed as a role on a web server.
The purpose of a web server is to host websites, services and applications that are used by users and developers.
Currently IIS 8.5 is the most stable and secure version your hardware can accomodate.
Most companies use IIS as a front end service that ties into a database. The front end merely translates the data to a web browser in an easy to understand format for anyone.
This isn't really my forte but something that I setup for developers to work on.
Thanks for reading.
Regards,
@trev03