To a webmaster, who has a blog or forum, the question can be where to put these, whether in Subdomains or subfolders, although individually both have advantages. For blogs, subfolders may be the better option because the value of the link which is sent to that blog will be distributed to the main domain and other subfolders under the domain.
With a subdomain, the blog or forum will be listed separately in the search engines results pages, which can be good for building a reputation for that blog or forum. The nature of the search engines, however, will not list more than two subdomains in the search results.
If these subdomains can prove, however, that they are independent individually and they are also relevant, they will be listed separately. The search engines normally, will not treat subdomains as independent of each other and instead attach some association between them.
Sub domains and How Do They Affect SEO
The search engines algorithm or ranking procedures for multiple subdomains is hard to prove that its relevance is independent of the other, and that these are treated as the same. If relevance is proven independently (which be hard to achieve) then the individual subdomains will be shown in the search results.
If multiple subdomains are highly relevant for a search query, then it is still possible that these subdomains will rank independently in the search results. So, if you add a forum so that you can be of much help to prospective customers who want to learn more about your online company and what you are offering, you have three options to do these.
1-You can use a third party site and have the forum on their site. To get people to this forum they will just type in the URL search box forum, not your site.com.
2-Another option is to host the forum on a subdomain of your site. This situation can mean that the forum will be hosted on a special section of your domain.
3-An option will also be hosting the forum on a subdirectory of your website. This option will mean that the forum will be hosted on the main section of your domain.
So, considering all these options, webmasters may ponder where to host these forums for best results in search engine optimization. The answer can probably be on the subdirectory because this is where the forum content that people will have more tendencies of attracting links, which is good for SEO.
It is important to note that contents that are getting the more number of links are the more relevant sites, in the eyes of the search engines and even label these sites as the trustworthy ones. So it will be the better option to host it on your own domain and not on another site, so that the value of the links will be for your site.