Do-Follow for More Reader Activity
Nofollow
Google introduced the nofollow attribute in 2005 to reduce the effectiveness of certain types of spam, thereby improving the quality of search engine results, and reducing spam in general. It was designed by Matt Cutts and Jason Shellen from Blogger.com webspam team. Its effect was described to remove the PageRank value of the link.
Different search engines treat links with nofollow differently. Google does not count the link as a vote, or index the target page if previously not indexed. Officially Google does not even make a note of the existence of the target page. Yahoo! the link, and may index the page, but the link won't give more value to the target. Other search engines may, or may not care about the attribute at all.
Some links have been tagged nofollow in Wikimedia software since the introduction in 2005, but site wide adding of nofollow to all external links in the English language Wikipedia happened only in January 2007. Blogger included attribute in comments and backlinks from early on. It was included by default in Wordpress comments from version 1.5 forward.
Do-Follow
Lately, especially after the introduction of nofollow to Wikipedia, nofollow has begun to be seen also as a negative thing. On blogs, commenting blogs has always been a way to market one's own blog, and after the introduction of nofollow, this has been less effective. Some bloggers claim that they now see a higher amount of spam comments, allegedly because to get the same effect spammers need to spam more.
Before nofollow those who comment regularly on a blog would also get many backlinks for free. Now that most blogs are nofollow, there is less reason to become a regular, or to comment at all. do-follow movement consists of bloggers, who wish to reward, and encourage commenting by giving back comments their backlink value.
How to Join
On Wordpress blogs there are many plugins for removing the attribute. Some plugins offer extra features, like nofollow for first time comments, or nofollow old comments. The customizable nature of Wordpress templates, and plugins has brought many solutions to this problem. The most popular of the plugins can be found with a Google search for 'do-follow Wordpress'.
If you have a Blogger blog, making it do-follow is as easy as removing each occurrence of "rel='nofollow'" in the template. The template can be modified from 'Blogger Dashboard', under 'Template' - 'Edit The 'Expand Widget Templates' checkbox has to be checked to see the posts section of the code.