Creating a subdomain: when and why?

A subdomain is a separate address under your main domain. Technically simple, but the choice has consequences.

When it makes sense

For something genuinely separate: a test environment, a customer portal, an application, a support platform. Things with their own software and their own audience.

When it does not

For content that is part of your website. A blog on a subdomain builds its own authority instead of strengthening your main domain. Put it in a folder.

What you have to arrange

A DNS record and a certificate. Note: a standard certificate does not automatically cover subdomains — that is the most common surprise.

Security

A forgotten subdomain still pointing at a removed service can be taken over by somebody else. Delete DNS records you no longer use.

Keep it readable

A short, obvious name. If you have to explain what a subdomain is for, pick a different name.