# Subdomain > A subdomain is a prefix on a domain that points to its own destination, as in app.example.com under example.com. It is created in DNS and can be pointed at a… Source: https://northerngo.com/glossary/subdomain/ Language: en Updated: 2026-08-28 --- **A subdomain is a prefix on a domain that points to its own destination, as in app.example.com under example.com. It is created in DNS and can be pointed at a completely different server from the main site, which is why apps, documentation and staging environments so often live on one.** ### What a subdomain actually is In `app.example.com`, `com` is the top-level domain, `example.com` is the registered domain (often called the apex or root), and `app` is the subdomain label. You create one by adding a DNS record for that name — typically a [CNAME record](/glossary/cname-record/) pointing at your host, or an A record pointing at an IP address. You do not buy it, you do not register it, and you can create as many as you want on a domain you control. Because the destination is independent, a subdomain can be served by an entirely different platform from the main site. That is what makes it the standard place to put an app: `example.com` stays with your marketing site while `app.example.com` runs the product. NorthernGo works the same way — apps on the Premium and Pro plans publish to `.northerngo.com`, or to a custom domain on Pro. ### A subdomain is a separate origin, and that has consequences This is the part that surprises people. For browser security purposes, `app.example.com` and `example.com` are different origins. Practically: - **localStorage, IndexedDB and cache storage do not carry over.** A user logged in on one is not logged in on the other unless you deliberately share a cookie scoped to `.example.com`. - **A [service worker](/glossary/service-worker/) registered on one does not control the other.** Each host needs its own. - **HTTPS certificates must cover the exact hostname.** A certificate for `example.com` does not cover `app.example.com` unless it is a wildcard or lists both names. ### Subdomain or subfolder? For SEO this argument has run for years and the honest answer is that both work. Google treats subdomains as part of the same site when the relationship is clear, but signals consolidate slightly more reliably in a subfolder. Where it genuinely matters is operational: a subfolder needs the same server to handle both, a subdomain does not. If the app is a separate deployment, a subdomain is the simpler and more robust choice — see the [custom domain guide](/resources/connect-custom-domain-ssl/) for pointing one at a published app. --- NorthernGo is an AI-powered platform for building production-ready web apps with zero coding. Local AI generation via WebGPU is unlimited and free, and you own all generated source code. https://northerngo.com/