Internet Information Server (IIS) is one of the most popular web servers from Microsoft that is used to host and provide Internet-based services to ASP.NET and ASP Web applications. A web server is responsible for providing a response to requests that come from users. When a request comes from client to server IIS takes that request from users and process it and send response back to users.
Internet Information Server (IIS) has it's own ASP.NET Process Engine to handle the ASP.NET request. The way you configure an ASP.NET application depends on what version of IIS the application is running on.
Internet Information Server (IIS) includes a set of programs for building and administering Web applications, search engines, and support for writing Web-based applications that access databases such as SQL Server. With IIS, you can make your computer to work as a Web server and provides the functionality to develop and deploy ASP.NET Web applications on the server. You can also set security for a particular Website for specific Users and Computer in order to protect it from unauthorized access.
IIS helps organizations to increase Web sites and application availability while lowering system administration and cost of deployment. IIS 7.5 supports HTTP, HTTPS, FTP, FTPS, SMTP and NNTP.