Word Wide Web, or better known as the WWW or internet, is a network of computers linking together for the purpose of sharing information electronically. While there are so many different computers linking together, there has got to be some kind of rules or standards to follow, otherwise communication is going to be difficult. Just like English is a commonly spoken language among people from different countries, where most people understand and use it to communicate and get things done. There is a detail explanation or rather technical explanation of Internet at wikipedia if you are interested to have a detail understanding and the history of internet.
There are indeed some standard communication protocol that is in used in the internet, you may have heard of technical words like http, ftp, smtp, pop etc. that is commonly used by techies and internet users, these are actually the common languages or communication standards for different tasks used by the inter linking computers in the internet to communicate with each other. With these communication standards around, we can use things link web browser to browse a web page, FTP client to upload download files from internet, Email client to send and receive email messages easily.
So how does WWW work?
In those computers that are inter linked, we can basically classify some of them as web servers, and some of the as web clients, a web client (such as a computer with a web browser like Internet Explorer or Firefox etc.) usually request content (i.e. web pages) from the internet, and a web server (i.e Linux web servers, Windows Web servers) will send the requested web pages to the web client if it is the web server that is storing the web pages.
So how does these computers know each other ?
How do these computers know which is which ? Well, every connected computer has been assigned an identity called IP address (i.e. 126.96.36.199), this IP address is like the international passport number and it is unique, and web clients and servers uses this underlying identity to identify each other.
So how can I memorize all these numbers ?
This is why domain name (i.e. dotservant.com) is used to help human memorized these, a domain name is basically a more human readable form of address, each domain name is unique and can be map to one or more IP addresses. When people request for a web page, instead of entering the IP address in the web client, a domain name can be used instead and there are specific computers called domain name servers that stored information of which domain names pointing to what IP addresses, and these domain name server are there to help serving direction information to the proper web server and clients.
Now that you have a overall understanding of the world wide web, you can go a little deeper in to What is Web Hosting ?