Here's a intro on web-sites for newbies.
Please don't nitpick and point out technical errors. This is stated in simple terms for better understanding from a newbie's viewpoint.
For a web-site, you need 3 things.
1. Domain (a .com, .net, .org, .in, etc.)
2. Hosting (server space)
3. Content and design.
All the three things are separate with separate costs. You can take all 3 from same person or all 3 from 3 different person. The last one can be managed on your own as well.
Let me start with a server. A server is a high capacity computer which remains on and online 24 hours a day, 7 days a week. Files on a server can be accessed without a domain name with an IP address as well.
But how convenient is a website if you have to type *212.100.33.56 to access it? Or if you have to send an email to info@212.100.33.56. So a domain name is used for convenience and clarity. When someone enters
www.yourdomain.com in his browser, that domain name is resolved to an IP address, you are forwarded there and files kept there are displayed.
This is how all the sites are made. You don't need any specific example for this.