All new domains must be registered with a domain name registrar.  Public Registrars are companies who deal directly with you the buyer.  They in turn get their inventory of domain names from the Registry for that extension (TLD).  The Registery has a contract to handle certain extensions and all registrars pull from their inventory of domains names.  For example, Verisign is the registry for all .com and .net domains. You cannot register domains directly with them.  Instead you can register domains with the hundreds possibly thousands of public registrars. Most registrars handle many different extensions and thus serve as middlemen between the registries and you.

So for any domain name that is not already owned by someone you have to register the domain with a domain name registrar.  Not all registrars are equal.  Many registrars have been created by "investors" in domains in order to have direct access to the Registry inventory.  Now that doesn't mean that all of them are just too make it easier for the high value investors and it also doesn't mean they don't have to meet certain standards.  If you want to find out how difficult or easy it is to become a registrar check out this link to ICANN.  If you want a list of the current registrars check out this link ICANN Registrars.

When determining what registrar to use there are a couple things to consider:

Price  - How important is price to you?  More important than Security, Ease of use, lack of support, etc.?

Security - What kind of domain names are you registering or buying from others and transferring to your registrar?  Do you really want you generic laptops.com at a registrar you barely know anything about?

Ease of Use - Do you need something that is almost intuitive or can you sacrifice that for cost since your going to register 1000's of domains.  Do you need bulk registration.

Support  - Do you want a company that will get back to you within an hour with an answer or is price more important?

Reputation - Does the registrar have a good reputation in the industry?

Other Services - Do you need a place that will provide a blog, web site and forum, or do have separate hosting, etc.  Is it easy to transfer a domain once you've bought it?

You'll notice that most of these questions go back to why your registering domains.  Are you registering thousands of domains, or just a few, are you parking, developing, reselling, etc.?    If you haven't thought about these questions I suggest checking out our Choosing Domain Name section. 

This is just the tip of the proverbial iceberg so we have set aside an entire section on the web site devoted to Registering Domains.