If you're not quite sure exactly what a domain is, you should watch the previous tutorial.
When you're trying to decide what domain name to purchase for your website, there are a few things you should know and keep in mind.
Domain names can be hundreds of characters in length, but the shorter the domain, the better.
Domain names can contain letters, numbers, and hyphens. You should avoid using hyphens, if possible, since that does make it harder to say your domain name to someone; being able to easily communicate your domain name is important.
As domain names get shorter, so too do their likelihood of being available for purchase, so you may not be able to buy your first choice.
You'll also need to decide what top-level domain, or domain extension, to use for your domain name, such as .com, .org, .net, .info, or .us.
It really doesn't matter anymore; you can choose whichever sounds best and is available. If the .com domain of your choice isn't available, maybe the .net version is.
To find out more about purchasing a domain name for your site, and how to check if a domain name is available, watch the tutorial immediately after this one.