The term 'custom domain' is one that is thrown around by various products and websites to mean subtly different things.
Since it's central to the work that we do at Cloakist, we thought we'd better explain exactly what it can mean.
1. Simply, a domain
The simplest definition is that a custom domain is a domain you purchase from a tool like GoDaddy, Namecheap, or millions of other domain name registrars, which means that you then own the domain (e.g. most-delicious-cakes.com) and can do things like send emails from that domain, or put a website live at that domain.
On a technical level, what's happening there is that the service you use (GoDaddy, Namecheap, etc.) takes your request to register most-delicious-cakes.com, checks to see if it's available, and if so lets you pay to register it.
Once you pay, the service ensures that a centralised database (e.g. ICANN's) is updated with the existence of your domain, and knows where to direct traffic to that domain.
Traffic could be an inbound email, or a viewer trying to access your site. Usually, that traffic will get directed to some kind of server, e.g. Wix's server if you build a simple site using their tool.
People who are talking about this definition of a custom domain might also use the terms 'domain name', 'custom URL', 'vanity domain', 'vanity URL' or just 'URL', to mean the same thing.
2. A feature of a product, that lets you use your domain with it
This is where it gets a little confusing. I'd say that among people who live in the tech world, the more conventional definition of 'custom domain' is:
A feature of a product (e.g. Squarespace) which means that users of that product are able to move some kind of site built with that product to their own domain.
These days, we create a ton of sites using third-party products. Most obviously, we create sites using site-builders like Wix and Squarespace. But we even create sites if we use tools like Google Docs, Trello, Notion, ClickUp, Airtable, and tons of Microsoft products.
You know you're 'creating a site' when the result of your work with some product is that a new site exists which didn't before.
That's where the second definition of 'custom domain' comes in. These days, many products which let you build sites also allow you to move the site you built to your own domain. That's what Wix and Squarespace do, for instance. Sometimes, they even let you rebrand the site a little – for instance, if you pay Wix and Squarespace, they'll remove their branding from the site you made.
So 'custom domain' in this instance is a feature that products can offer to their users. I'd argue that tends to be how the phrase is most commonly understood, at least by people who spend a lot of time around digital products.
Hope this article helped clarify this topic a little. We care about this because Cloakist's job is to enable the custom domain feature, in other words the second definition, for products that don't offer this feature. We also then allow rebranding and whitelabelling. You can find out more about that here.
If you have any questions, drop into our live chat!