If you notice in my signature, there is a link. This is a signature, do-follow link, because it allows someone to click on it to "follow" to the website. A no-follow just shows a link but you'd have to copy and paste. These don't give value in the search engines due to being no-follow. However, you shouldn't abuse having these links. Don't just go post a short or very similar to another's response just to get the link. Provide useful content when forum posting.

A profile backlink is like a signature link, but only exists on your profile and is only one link, where a signature link shows up every time you post. I hope this helps you some.

Hey forum profile link is the link in your forum profile.
We people use it to build links for websites.
It doesn't show up in backlink count but always good for seo jump.

See those links below - they are forum backlinks...