Your own website
Now a days anyone can create a free or inexpensive website using popular online content management systems.
But your are tied to their URL like
Domain names provide a neat, friendly and much more memorable alternative such as http://mysite.cool.
Your own email address
Of course you can also use your domain name as your email addresses. There are many popular free email providers out there (such as Hotmail, Yahoo, Gmail etc.)
but you can also use your own domain such as firstname.lastname@example.org setup with an inexpensive email service provider.
You can even setup email forwarding to your favorite popular free email provider.
Your own identity
A domain name is a unique address, like any physical address or phone number, that people use to find you on the internet.
It's simply a string of characters which usually spells out a word, a company name or person's name, for example yourname.com or yourcompanyname.net
Promote your interests
Why stop at your own name or company name?
You are more than a name. You have hobbies, activities, interests, products, services ... Promote them.
Tell the world who you are online with a custom website, and a unique short friendly meaningful domain name.
Find one that really conveys your message to the world and own it.
Protect your identity
A domain name is unique, like you. You may not want someone else owning your name or a similar domain name to yours.
Often people and companies will purchase a domain name to protect their identity, regardless of whether they intend to use it or not.
Domain names have become increasingly valuable over the years, as the 'better quality' domain names become registered quickly.
They can be bought and sold like any commodity. Ownership is easily transfered after a sale is made and the new owner can choose to use it, redirect it to their own site, keep it unavaiable, or sell it for profit.