Domains create your address on the internet. When you own a domain, you can tell people to go to the URL www.alpineweb.com and they will see whatever content you've associated with that domain. Every domain name is matched to an IP address and follows the Domain Name System (DNS).
Without a domain, every website would only be identified by the IP address. Imagine that instead of typing https://www.alpineweb.com into your web browser, you had to remember 220.127.116.11, AlpineWeb's IP address. Now imagine remembering strings of numbers for every website you ever want to visit!
Domain names make it much easier for people to use the internet. It's the difference between using latitude and longitude to get somewhere and using a street address to get somewhere.
Let's use support.alpineweb.com to show how domain names work. Even though it is a little confusing for most people, domain names are technically read from right to left. No one reads them like this when telling you to visit support.alpineweb.com, of course! But reading from right to left creates a funnel: the address goes from the very general (top-level domain) to the very specific.
Top-level domains (TLDs) like com, net, and org hold the right-most position in a domain name. Every country can have their own TLD, too. Every domain name must end with a TLD. In support.alpineweb.com, the TLD is com.
.com is a TLD
Second-Level Domains (and Beyond)
Whatever is directly to the left of the TLD is called the second-level domain. In the example support.alpine.com, alpineweb is the second-level domain. Anything to the left of the second-level domain is the third-level domain. In this case, support is the third-level domain. This can go on and on as long as there are more domains to the left. The more levels you use, the more specific your address is.
alpineweb.com is a second level domain
When you purchase a domain name, you buy the right to use a specific TLD and second-level domain. So, you'd buy the right to use www.alpineweb.com (or whatever you'd like your domain to be). If you want to add further domains like support.alpineweb.com, you don't have to pay for another domain name. This is considered a subdomain and you can set it up through your domain management system, like cPanel.
support.alpineweb.com is a third level domain or subdomain
Now that you know the basic concepts surrounding domains, you're ready to learn how to register your first domain! (See: Registering a Domain Name (Main URL)