How stuff works explains it in a very good graph
I was very confused by the Wikipedia explanation but here's how someone simple minded like me understand it. DNS serves as a host of a "dictionary", this dictionary maps the IP address to a domain name and vice versa to help people locate the correct website.
Here's what I also learnt :
I registered http://www.mashbean.com
I plan to "hack" it and link it to this blogspot soon. May be later one I will chain it to a WordPress or a personal website regarding my personal portfolio.