Nofollow, Dofollow are HTML tags (rel=”NoFollow”/re=”DoFollow”) that instruct search engines how to treat links posted on a page when they crawl it. Search engine spiders index pages as they crawl the web and if they come across a new link they will start to include that in their search results. However, if a link has the NoFollow tag they will ignore it and the backlinks will not count towards your website incoming link total and will therefore not help your web search optimization or Google SEO.
The problem with the NoFollow, DoFollow attributes is that they can’t be seen on a website without checking the code. It is therefore very easy for people to waste their time posting hundreds of comments that will have no impact on their search engine rankings because the links are ignored.
Identifying NoFollow DoFollow Links
There is a great way of checking whether a website uses DoFollow links or NoFollow links and this is SEO Toolbar by Moz.
Download from here: http://moz.com/tools/seo-toolbar and choose your Browser.
Add Add-ons to yor Browser
In the bar that appears after you launch the toolbar, click on the “Highlight links or text” marker icon. You can then activate highlighting of followed links and no-followed.
Once you have installed the extension into your Firefox browser it highlights links according to whether they are DoFollow or NoFollow. Pink highlighting depicts a NoFollow link and Green shows DoFollow links. If links in a blog or forum are highlighted in green then this is a good place to insert your comments and links to your site as part of your web search optimization strategy. If, not, links from these sites can still be useful for Google SEO and driving traffic to your blog but they will not count as valid backlinks.