What is a domain?
A domain is a name of a website (e.g., www.xyz.com). In general, it is a name you have chosen for your website. Domain name is a unique identity (online name Card) on the internet.
A domain is like an online Business address where Internet users can access your website. Generally, computers use IP addresses (e.g., http://126.96.36.199), which is nothing but a number series of your domain name.
In simple terms, you can browse google using the domain name www.google.com (or) using IP address 188.8.131.52 as both will give you the same result.Since it would be real painful for us to remember these numbers, domain names were developed.
A domain name can be any combination of letters and numbers, and it can be used in combination of the various domain name extensions, such as .com, .net and more.
The domain name must be registered before you can use it.
Every domain name is unique.
No two websites can have the same domain name.
If someone types in "www.yourdomain.com", it will go to your website and no one else's.
very nice explanation about domain