Domains – .com , .org , .in , .uk ,  

In early 1990s when web pages have become popular every website was in the form of “www. domain. com”. WWW became a synonym for the World Wide Web. Whenever you see a text in the form of “www. domain. com” you immediately know that this is a web address. But is www mandatory for web address?
The purpose of domains is to have some easy-to-remember names. These names translate to IP addresses which are needed to communicate over the internet. The domains as we use them in the internet business are organized in a hierarchical naming system. We have a few general-purpose top domains like com, org, net, country top level domains like us, uk, de (each country has its own unique top level domain), and special top level domains like mobi, aero, museum and others. Each of theses top domain has a second level of domain names where you can have anything you like (of course, if it is not registered yet). Each domain name must be unique and not longer than 63 characters.
The level of domains doesn’t stop there. Each second level domain can have any name as a third level of domain. WWW is such an example. Every domain (regardless of the level) must be associated with at least one IP address. Therefore “domain. com” and “www. domain. com” are different domains and each has its own IP address which can be the same. We may have various services associated with our domain like FTP or private access area. In such case it makes sense to assign each service to its own third level sub-domain. One of the services could be web pages at www sub-domain. But having the www domain is not mandatory. You could have your main domain pointing to your website. It is the perception of the people that each web address should start with WWW.
Majority of the domains have no other service than web pages. Therefore you don’t have to use www for your website. But it makes sense to create and configure www sub domain and redirect it to your primary domain. This way you will not loose visitors which will type www in front of your domain. It is also possible to do the other way–to redirect non-www address to www address. For this you need to configure DNS records also for www domain name and to check with your website how to do redirection there. Usually it can be done with.htaccess file.

With or without www you can have a successful website. It is up to you and to your taste which form you will chose. If you decide to use the shorter and simpler version without www you can still make it clear that this is a website by writing “http://example.com” and everybody will know that this is a web address.