A domain name is essentially a signpost on the Internet. Almost every website you've ever been to, and every email you've ever composed, has used a domain name in its address.
People register domain names in order to 'stake a claim' to a particular name -- whether for business or personal reasons. Once a domain name is registered to a person or company, it is that person's to use exclusively as long as they continue to pay the yearly renewal fee and abide by the terms of use.
