What is IIS? Why is it used?

Internet Information Services (IIS) is created by Microsoft to provide Internet-based services to ASP.NET Web applications. 

It makes our computer to work as a Web server and provides the functionality to develop and deploy Web applications on the server. 

IIS handles the request and response cycle on the Web server. It also offers the services of SMTP and FrontPage server extensions.

The SMTP is used to send emails and use FrontPage server extensions to get the dynamic features of IIS, such as form handler.