Domain names are often seen in analogy to real estate in that domain names are foundations on which a website can be built, and the highest quality domain names, like sought-after real estate, tend to carry significant value, usually due to their online brand-building potential, use in advertising, search engine optimization, and many other criteria.
A handful of domains will have restrictions on them, which means you can only purchase them if you meet or exceed certain criteria or have authorization (some examples are .gov, .edu and .mil). But most extensions are available to everyone. In fact, most country code Top Level Domains (ccTLDs) are available for anyone to purchase, even if you don't reside in the country code in question.
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.