IIS used for SMTP server when we need to send mail .

There are following purposes of IIS...

- Manage Web Sites/Pages

- Serves requests and send responses back to the client

- Run/execute Server side scripts of the requested pages...

- Provide different type of security on web sites/pages...

IIs is web server which will accepts the request from client and serve the request ,means it will send the requested web page to client

IIS serves as tool to respond to the request of the client, the IIS recives requests and handle them the it sends back a server page ASP ASPX PHP JSP and so forth

IIS:It can be used for the Run Web Application.goto->run->inemgr->website ->newwebsite->create your on virtuval directory and run the your Web Application in this ISS sever.
Thanks