Sub Domain or Sub Directory:
The URLs and the navigation of a site do matter for SEO but the elements of site structure that affect SEO don’t end here. For example, take sub domains and sub directories. These are another example of a site’s structural elements that do influence how Google ranks results. While the difference between when a page is in a sub directory (also called a sub folder) vs when it’s on a sub domain might not be always huge, there are cases when it really matters if you use sub domains or sub directories.
The Difference Between a Sub Domain and a Sub Directory:
First we clarify the difference between sub directories & sub domain before we discuss about advantages and disadvantage. In sub domain our Urls will look like this: abc.yoursite.com / subdomain.domain.com.
we use sub domain part before domain this part for google and site visitors, that the content of subdomain and domain is different from each other.Sub domains are used for business sites. where blog is separate from site. i.e. blog.yoursite.com, Site with forum, forum.yoursite.com. There is not a rule when SEO Expert use sub domain and when sub directories but is your content is good and unique from your website, then you go with sub domain and if your content is not much different from your main content than you go with sub directories.
SEO Benefits of Sub Domains
It’s hard to say that sub domains are better for SEO or not because Search Engine Optimization (SEO) depends on many other factors. However, one of the cases when you would benefit from a separate domain is when you have multiple pages for a single keyword. Google generally limits the number of search result per domain, but this doesn’t apply on sub domains. For Ex. if you had domain with sub directories and have 5 relevant results, google will show only 1 or 2 of them, but if you had 5 sub domains 2 or 3 result per sub domain (10 to 15 altogether) will be shown. sub domain just to trick Google to show more results from your site ‐ this might not work and you will have wasted your time and effort.