When looking up a bare name in DNS, the network stack will add the search domains to it to form fully qualified domain names, and look up those as well. For example, if the domain search list contains "wikipedia.org", typing "en" in the browser will direct the user to "en.wikipedia.org". Some ISPs add their own search domains via DHCP settings, similar to how they add DNS servers and other networking information; if this is undesired, the user can change this setting to ".local".
If you have purchased domain names that you no longer need, you can sell them through Namecheap. When you are ready to sell, you can list your domain in our Marketplace for a fixed price. We will add your domains to our searchable list, visited by thousands of people every day. When you buy domain names from Namecheap, we guarantee the best available support from managing, to selling, to renewals.
Think of your domain name as a street address for your website. Without a domain name, you would have to tell customers to visit your website at an IP-based url such as 22.214.171.124/~yourwebsite instead of yourwebsite.com. The former is not very memorable or friendly to human eyes and will surely result in not that many visits to your website. While it is not mandatory that you have a website domain name, nor is it mandatory that a domain you own be attached to a website, for a successful online presence you truly will want to get your own domain name to ensure your website has the proper air of professionalism and appropriate branding.