What is a Subdomain?

Everything you place in your public folder on the server becomes available for anyone on the Web to see (assuming they know the address of your site and the files you’ve placed there). If you’re just putting up a handful of static, HTML pages which you want to make available to colleagues, friends, or family by sending them links, then keeping all of your files within this one folder may work fine. As soon as your site starts to get more complicated and targeted towards a broader audience, however, you should consider a new organization strategy.

Consider this scenario: you want to have a personal blog on your new web space, where you share pictures and short written pieces with family, friends, and colleagues. In addition, you’re working on a large research project that requires you to build a web-based repository of digital images related to your discipline. You want to use one application (say, WordPress) to manage your personal blog. For your research project, you’ve settled on another open-source application (say, Omeka). Both of these are applications that need to be installed on your web host, but you can’t just put them both at your main domain name – if you did, both sites would quickly experience conflicts and errors. You need to cordon off separate spaces for your different web “properties.”

A subdomain is one way of organizing and separating content on your site. Consider Google’s website and suite of apps.

Google’s main search engine is located at “google.com“.

To access your Google email account, you’re directed to “mail.google.com“. When you view an email, draft messages, or change your email settings, your web browser is looking for that content within the part of the site indicated by the “mail.google.com” URL.

If you next want to access Google Drive, you’re instead directed to “drive.google.com“. Your documents live within the portion of the site indicated by this different URL.

The difference in the URL corresponds with which application you’re using: mail, drive, or just the main search. You can also see this at work when you use other Google applications, such as “calendar.google.com” and “maps.google.com“. Each of these is a different subdomain of google.com.

As you can see the subdomains serve two purposes: they help to organize the site from a technical perspective and they help users visually identify that they are in a new/different space. As you work on your site, you’re welcome to create as many subdomains as you like, and in each subdomain you can actually create a distinct website. Keep in mind, however, that the domain name you receive when you sign up for Emerson.build is already itself a subdomain of emerson.build. This means that when you create a new subdomain of this domain, it will be of the form: subdomain.yourdomain.emerson.build.

Subdomains are not the only way to organize your domain space, however. You can read more about another organization strategy in the “Subdomains vs. Subdirectories” portion of this documentation. When you’re ready, we also have additional information on how to set up subdomains.