What is a domain name?
Domain name is a string or letters to identify a computer or network resources on the internet. It is a string, but beneath this string, are sets of numbers(10.71.170.5, 184.108.40.206 etc) that computers can easily identify. Examples of domain name is NaijaTech.com.ng, NaijaLoaded.com.ng, www.Nairaland.com, Facebook.com and millions of domain names on the internet.
Levels of domain name
Domain is categorized based on level. Starting from the top, we have the top-level domains(TLDs), these are domain names that have the generic suffix like .com, .net, .org, .info, .gov and the likes for example, nairaland.com, facebook.com are examples of top level domain. Also available, is second level domain. Under this type, we have other attachments to the generic suffix of the top level domain. For example, naijatech.com.ng, naijaloaded.com.ng are examples of second level domain name. For the .com.ng domain name for example, it gives internet users an idea that the owner of this domain have a nigerian connection. Another popular example is .co.uk domain name, it gives an idea the domain name have a uk connection. Now, if you have an idea that does not need to be attached to a particular country, you can simply use the top level domain name e.g .com, .net etc. Apart from the ending suffix, and country attachment, there is no other big importance or implication of choosing any of this domain name types.
To register a domain name on the internet, you have to register with Domain name registrars. See website you can register any type of domain name here.
Personally, I discovered to register a .com, .org, .net domain name is more expensive than registering a .com.ng domain name. For further details and other technical explanations, you can visit wikipedia website information about domain names.
You will like topic on website to get cheap, affordable domain name and web files hosting service.
Reference: What is a domain name(wikipedia)