A domain like blog.example.co.in looks like one string, but it is built from named, nested parts, read right to left. Knowing the parts makes DNS records, in a later lesson, far easier to understand.
| Part | In blog.example.com | What it is |
|---|---|---|
| Top-level domain (TLD) | .com | The broadest category, assigned by a global authority — covered in depth next lesson |
| Second-level domain (SLD) | example | The actual name you register and pay for |
| Subdomain | blog. | A free, optional prefix you create yourself, pointing anywhere you like |
You register the second-level domain plus the top-level domain together — example.com as a unit. Everything in front of that, like blog. or shop., is a subdomain you create for free, entirely under your own control, once you own the base domain.
A subdomain is a free way to split your site into logically separate sections that can even point at entirely different hosting:
| Subdomain | Common use |
|---|---|
| www.example.com | The conventional address for the main site — often set to behave identically to the bare domain |
| blog.example.com | A separate blog, sometimes on entirely different software or hosting |
| shop.example.com | A separate store platform |
| api.example.com | A backend API, served separately from the main website |
| mail.example.com | Often used for webmail access |
Because each subdomain can point anywhere independently, a single domain can quietly be serving several completely different platforms behind the scenes — a marketing site on one host, a blog on another, an API on a third — while looking like one seamless site to a visitor.
www.example.com and the bare example.com are, technically, two different addresses — www is just a conventional subdomain, left over from the early web. Most sites configure both to work and redirect to one consistent version, so a visitor never notices the difference. Picking one as canonical and redirecting the other is a small, standard setup step covered in the connecting-a-domain lesson.
A domain can technically be registered with more than one dot before the TLD in some cases — example.co.in is a real pattern, not a typo, covered in the next lesson on TLD types. The parts described here still apply; the base registered name is just slightly longer.