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What is a subdomain — and when should you use one?
A subdomain is a named division of your domain: in portal.example.com, "portal" is a subdomain of example.com. Technically it's just another DNS record, so it can point anywhere — a different server, a different product, a different system entirely. That freedom is exactly its power, and exactly why it's easy to use wrong.
How a subdomain actually works
DNS resolves each subdomain independently: www, portal, and api under one domain can live on three different servers on three continents. That's how companies run their app, their status page, and their marketing site as separate systems under one brand.
We use them the same way: on our own platform the marketing site and the client systems (portal, e-signing) run on separate subdomains, so each surface can be secured, scaled, and deployed on its own schedule.
Subdomain or subdirectory? The SEO answer
For content — services pages, guides, a blog — a subdirectory (example.com/blog) usually wins: search engines treat it as part of the main site, so every page strengthens one domain's authority instead of splitting it across several smaller ones.
Subdomains earn their place when the thing really is a separate system: an application with its own login, an API, a regional or product-specific property. Rule of thumb: content in subdirectories, systems on subdomains.
The operational side
Each subdomain needs its own DNS records and TLS coverage (a wildcard or per-name certificates), and browsers treat subdomains as separate origins for cookies and scripts — a security feature that isolates your app from your marketing pages.
This page you're reading practices what it preaches: it lives in a subdirectory, because it's content that should strengthen the main domain.
FAQ
Do subdomains hurt SEO?
Not inherently — search engines handle them fine. But content on a subdomain builds that subdomain's authority rather than your main site's, so for guides, services, and blogs a subdirectory usually compounds better.
Is www a subdomain?
Yes — www.example.com is technically a subdomain of example.com. Modern sites usually pick one form as canonical and permanently redirect the other, so both work and search engines see a single site.
How many subdomains can I create?
Practically unlimited — they're just DNS records under your domain. The real cost is operational: each one needs certificates, monitoring, and a reason to exist.