I apologize but i didn't get your question properly? You want to know about webhosting? or hosting services where some companies allows you to host any particular services on their servers. These services can be web, emails, DNS or file services.
In Webhosting (as you have opened the thread in IIS section) a Company (known as Webhosting Company) have server in their own datacenter on rented with some datacenter and they give some space to users and their customers to upload their webpages.
A webhosting company have to take care of Web as well as all other services like DNS, Emails, FTP etc. which are required for any client.
Thanks and Best Regards,
Milind Mohan Koyande