The first step of getting a website is registering your domain with a domain registrar. Don’t confuse this with hosting your domain, although the two are related.
Domain registrars are companies who keep track of who owns which domain name on the Internet. Like printed phone directories that used to list phone numbers you could use to reach someone by phone, the domain registration system is one big directory listing. Except instead of one company keeping track of the list and printing it, many companies (registrars) combine all their lists into one big shared list for the whole Internet to use. This is why someone can be anywhere in the world and type in www.kathleenpequeno.com and land on this website.
You “register” or “own” your domain by “buying” it via a registrar. That’s how I own www.kathleenpequeno.com, along with kathleenpequeno.org. “Owning” that domain name means that I get to use that name for a website, email, or anything else involving the domain name. Once you buy a domain, you tell your registrar where you want to host the files for it (see my post explaining web hosting). You can buy one domain name or one hundred.
Cost: less than $10 per year per domain. Yes, you pay separately to own the .com and .org versions of a name, since each name is totally independent of the other.
Best practices: Once you buy a domain name, you must continue to renew it. If you don’t renew, then you don’t own your domain anymore. Then whoever does own it can do whatever they want with it. That is bad.
You can buy a domain name for more than one year at a time, although I actively discourage clients from buying more than three years at a time, since that is enough time to lose your account information. This happens more often than you might think.
Similar words: Domain registration, registrar, owning a domain, registering a domain, purchasing a domain/domain name, domain renewal, registrar account.
Example: I use and recommend http://gkg.net to register my domains.