A handful of domains will have restrictions on them, which means you can only purchase them if you meet 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 in question.
A domain name registration is simply reserving your website's name for a specified period of time. The two parties involved with a domain registration are generally the user who is registering the domain and the domain registrar. The domain registrant is the user who actually registers the domain name and the domain registrar is the company who helps that user with their domain registration.
1&1 Internet — This is primarily a large web host that is also a domain name registrar. Like all registrars, there are different charges for different domain suffixes. For example, at the time I last checked, you pay $0.99 for a ".com" on your first year, then $14.99 per year thereafter. The fee includes private domain registration, which means that your particulars are hidden from public view (done by registering the domain in the name of a proxy company). You also get a free email account and unlimited email forwarding, DNS management, a free SSL certificate for your domain, etc. Both credit card and PayPal payments are accepted by this registrar.
Some domain names are only available at auction. For now, we’ve chosen to feature buy it now domain names because they are often available immediately. We are working to improve our search engine to make it easier for advanced users to choose whether they want to include domains at auction (or domains with hyphens and numbers) in the search results.