Blogs: comment permalink or nofollow

so i have noticed that some comments on blogs are no follow and some are comment permalink. does anyone know why that is? does the blogger decide which comment will be comment permalink or nofollow?

i am quite puzzled by this, please advise

thanks

Lots of people think that it is a good idea to nofollow all links posted in blog comments. This discourages people who make comments just to get a backlink. It makes for a better blog because the comments are left by people who have something to say and who are truly interested in participating in the discussion.

ok, but how do they mix and match? is it possible that the blog owner decides which comment will be no-follow and which will be permalink? please advise

All links posted in comments by visitors are nofollow. Only links posted by the author are followed (if the author wants that).

If you need links. Instead of posting comments on blogs, post interesting ideas on your own website. They will attract natural links and traffic. If you post comments that content is on someone else's site and attracts traffic to them.

There are tools that are searching for blogs with "do follow" comments like findblogfinder. Personally I don't think it worth using them.

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It depends. Wordpress by default will mark all comments as nofollow. Some alter their template or use a plugin so they can choose which comments to tag as nofollow. I use a plugin to actually enable all comments to be "dofollow" (meaning, without the nofollow attribute): Why you shouldn't use nofollow links
The argument for using nofollow is that it will prevent spammers from spamming your blog. Personally, I just use Aksimet to weed out the spam and allow dofollows because I think it allows for a better flow and exchange of ideas between blog owners. If another blog owner wants to put a meaningful comment on my site, why not send a small fraction of my pagerank their way? If they want to leave some BS comment just to get a free link, I just delete it.

I also use the NoFollow Reciprocity plugin for Wordpress, which automatically tags all outgoing link to big sites which use nofollow as nofollow (like Wikipedia). Big site owners like Wikipedia don't need the linklove as much, so they mark all outgoing links as nofollow. So why not give nofollow links right back to them?