A subdomain is an extension of your domain name that lets you create a separate section of your website under the same root address.
So for exaxmple, if your website is your-big-idea.co.uk, a subdomain might look like blog.your-big-idea.co.uk or shop.your-big-idea.co.uk.
They allow you to add new sections to your website while keeping everything tied to the domain you already own.
How subdomains work
Your domain name is made up of a few distinct parts that work together.
The TLD (Top-Level Domain) is the ending, like .co.uk, .com, or .net. The SLD (second-level domain) is the main part of your name, like “yourbusiness”. Together, they form your root domain — the main parts of a web address you can register.
A subdomain sits in front of the root domain, separated by a dot, and acts as its own distinct address within your website.
Subdomains are created through your domain’s DNS settings, and they’re easy to set up in your account.
See also: DNS – How Do Websites Get Found Online?
What are subdomains used for?
✓ Online stores: shop.yourbusiness.co.uk
✓ Blogs: blog.yourbusiness.co.uk
✓ Customer portals or login areas: app.yourbusiness.co.uk
✓ Different regions or languages: fr.yourbusiness.co.uk
✓ Testing and development: staging.yourbusiness.co.uk
What’s the difference between a subdomain and subdirectory?
A subdirectory puts extra content within your main site structure, for example yourbusiness.co.uk/blog. A subdomain separates it out as its own address.
For most small businesses, subdirectories are the simpler choice and tend to keep your SEO value consolidated in one place. Subdomains make more sense when the content is genuinely separate, like a standalone web app or a distinct regional site.
Do you need a new domain for a subdomain?
No. Subdomains are created from a domain you already own, at no extra cost. If you don’t yet have a domain, that’s the starting point.
Can I protect my subdomains with an SSL Certificate?
Yes. If you’re running a subdomain that visitors can access, it needs its own SSL certificate to keep it secure. A standard SSL certificate covers your root domain, but won’t automatically extend to any subdomains you create.
A Wildcard SSL Certificate is the best solution for most businesses. It covers your root domain and all subdomains under it in one certificate, so whether you’re running shop.your-big-idea.co.uk, or anything else, they’re all protected.
See also: What are SSL Certificates?
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