I hope this is the right forum, I hope someone can help. I have a nice site that does very well with a good number of Google referrals, and I’m considering taking it to the next level by adding a forum so that it can have a community of some sort associated with it.
My hosting company has the option to add subdomains, which map to a folder inside the site. I’m just wondering whether a) there is actually any benefit to using a subdomain, and b) how this forks regarding spider indexing. Ie, I can make forum.domainname.co.uk which maps to domainname.co.uk/forum - so do I need to prevent robots from accessing /forum to encourage them to see the URLs as on a subforum, separate from the main site?
As a general rule, I would not use subdomains unless it provided a significant advantage for your users or if it is a function of your site that is so materially different that you want it separated.
You should use whatever functionality is best for your users because, at the end of the day, they’re the ones that will visit the site.
As far as I know, there are no big differences in SEO terms. To a spider, when it crawls mydomain.com, it will crawl as much as it can and for it doesn’t matter it is just a folder or subdomain.
Some companies (like sitepoint) decide to use subdomains because for them it is easier to organize different applications and functionalities (forum, articles, etc). Sometimes, you’re forced to use a subdomain because that application is not hosted within your own server (this is the case with this forum)