Just like how every house has a unique identifying address for the post office, every website has an address. This is referred to as the Domain Name.
You may have seen domain names like yourname.wordpress.com or www.mit.edu/~yourname. These are sub domains. They are like a flat address. In these examples, wordpress.com and mit.edu are the domain names.
If you are a blogger and you are using one of the blogging platforms like WordPress or Blogger and your address on the web is yourname.wordpress.com or yourname.blogspot.com, then the below 3 reasons will convince you to get a domain name.
Domain Name = Identity
Domain Name can be a big part of your personal brand online. If you have a personal website, it will be easy for your friends and acquaintances to find you at YourName.com. (Speaking from personal experience here!)
If you have a company, then the same principle applies. Having a website address like YourCompanyName.com will trademark your company and will make it easier for people to find your company online.
It is your personal or corporate brand on the world wide web!
Give Your Website Credibility
If you are running a business website, a domain name gives it credibility. Lets say you receive a professional email from an email ID – firstname.lastname@example.org, on a scale of 1 to 10, how much would you believe this company to be genuine?
Make Moving Easy
If you ever change your blog or web host, your domain name goes with you. I had a blog on sonysimon.blogspot.com. A few years later I decided to move on to WordPress. I had to inform my visitors about the change of web address (URL) and lost some followers in the process. If only, I had used a domain name back then!
If you need more help in choosing a name for your website, read my other articles here.