December 16th, 2008.
One question many site owners make as their website grows- â€œshould I use a subdomain or a subdirectory to place my blog in?â€.
This common question isn’t limited to just blogs– news sections, articles, careers sections… any grouping of content will at some point cause the question.
For those who don’t know- ‘news.google.co.uk’ is an example of a subdomain, where â€œnewsâ€ is the subdomain of â€œgoogle.co.ukâ€.
A subdirectory is a folder within a domain- e.g.- ‘google.com/analytics/’ where â€œanalyticsâ€ is a subdirectory (or folder) within â€œgoogle.comâ€.
While these may appear relatively similar, subdomains and subdirectories have different uses for a site, as well as different effects in a pages ability to rank in search engines.
Generally, search engines will allow pages within subdirectories to rank easier in comparison to pages within a subdomain. This reason being subdirectories inherit more authority from the domain name, whereas pages within subdomains inherit less authority from the domain (thus being treated similar to an external domain, although still receiving some of the authority from the main domain.)
So if subdirectories inherit more authority from a domain, why do companies choose to use subdomains?
Subdomains are used to segment a large amount of content on a site by a specific topic. If the number of pages are relatively high for a section (e.g. hundreds of pages), it may be logically better to place these pages within a subdomain rather than a subdirectory.
Otherwise, we recommend keeping within the content within the domain (i.e. using subdirectories)- this will make it easier for pages to rank better in search results as these pages inherit more authority from the main domain.