What is Subdomain?
A subdomain is a type of third-level domain that is created under a second-level domain, such as a blog or shop, under example.com, thus resulting in: blog.example.com or shop.example.com. A subdomain does not need a separate registrar to create one. A subdomain has its own hosting and content structure. However, it can still direct traffic and authority to the main domain. Marketers often use subdomains to segment big sites, create microsites, or run region-based campaigns. Marketers need to think through SEO issues because search engines are likely to treat subdomains as separate sites.
Examples of services offered in subdomains include support.yoursite.com, which provides customer services, events.yoursite.com, which registers for conferences, and m.yoursite.com, which gives mobile access to the content.
Related terms: root domain; subfolder; URL structure; microsite