iFastHostingWhat is a subdomain?
A prefix added to a domain you already own, letting you run a separate section of your site under the same name.
A subdomain is a prefix added in front of a domain you already own — blog.yourdomain.com or shop.yourdomain.com rather than yourdomain.com itself. It lets you run what functions as a separate site or section under the same overall domain name, without registering anything new.
Where the name comes from
Domain names read right to left in terms of hierarchy: yourdomain.com is the domain, and anything added before it as a prefix is "sub" to that domain — hence subdomain. www is itself technically a subdomain, just one so common that browsers and users barely notice it as one.
What people actually use subdomains for
- Separating a blog or documentation section from a main marketing site, especially when the two are built on different software.
- Running a staging or test copy of a site —
staging.yourdomain.com— separate from the live version. - Giving a web application its own address, such as
app.yourdomain.com, distinct from a marketing homepage at the root domain. - Regional or language versions of a site, such as
us.yourdomain.comalongside the main version.
Subdomain vs addon domain vs a completely new domain
| Option | Example | When to use it |
|---|---|---|
| Subdomain | blog.yourdomain.com | A section of the same overall site or brand |
| Addon domain | anotherbrand.com, hosted on the same account | A genuinely separate website or brand you also own |
| New domain registration | A domain you do not currently own | Starting something with no existing name to build on |
A subdomain does not need to be purchased separately — it is created for free within a domain you already control. Adding a domain to your hosting account covers the addon domain case if what you actually need is a second, independent domain name.
Does a subdomain need its own hosting?
Not necessarily. A subdomain can point at a folder on the same hosting account as its parent domain, which is the simplest and most common setup, or it can be pointed at a completely different server or third-party service. The first case is a control panel setting; the second is a DNS record pointing elsewhere. Pointing a subdomain at a folder covers the first, and delegating a subdomain covers sending it somewhere else entirely.
Does a subdomain need its own SSL certificate?
Yes, in the sense that a certificate has to specifically cover it — a certificate issued only for the root domain does not automatically secure every subdomain unless it was issued to include them. Most control panels handle this automatically when a subdomain is created and SSL is enabled, but it is worth checking your control panel's SSL section for the subdomain specifically rather than assuming it inherited the main site's certificate.
Related reading
Creating blog.yourdomain.com or shop.yourdomain.com is a control panel setting, not a DNS change alone. Here is the whole process.
How to add a domain to your hosting accountA domain has to exist inside your hosting account before DNS can point at it. Here is where that setting lives and how to use it.
How to delegate a subdomain to another serverHanding DNS control of one subdomain to a different set of nameservers, while everything else on the domain stays exactly where it is.
Do I need both a domain and hosting?Yes. A domain is an address; hosting is what the address points to. A website needs both before it can go live.