A domain name registrar is an organization or commercial entity, accredited by a generic top-level domain registry (gTLD) and/or by a country code top-level domain (ccTLD) registry, to manage the reservation of Internet domain names in accordance with the guidelines of the designated domain name registries and to offer such services to the public.
Domain registration is a simple process in which you will be required to give contact information that will be publicly available through the WHOIS database. Anyone can go to a WHOIS search engine and enter a domain name to see who has registered it. Registrars require that this information be accurate and true. If you feel uncomfortable providing personal information, there are some registrars that will act as your proxy, supplying their information in place of your own as the contact for the domain. There may be a small fee for this service and potential drawbacks to balance against the ability to maintain your privacy, so read the Terms and Conditions carefully before deciding to opt for a domain by proxy.
Also important, be sure you will own the domain name, as some registrars maintain control over the domains they register. And be sure you retain the option to transfer the domain to another registrar, if you wish. There might be an initial period after which this becomes possible. Look for any fees that might be incurred as a result of transferring the domain. This could become important down the road if you wish to take advantage of another registrar's products or services.
Upon completing the domain registration process, it will take a period of hours to a few days to be able to see the domain online. The domain can be "parked" with an "in construction" page that acts as a kind of placeholder. Parking a domain is very inexpensive and most registrars offer this service for a small fee to give you time to come up with content. Once a registrant is ready to supply content, a web server must host the domain. The registrar might also provide hosting services, or you may wish to transfer your domain to another web hosting company.