Now a days NoFollow & DoFollow is damn important thing in the field of Search engine optimization. Search Engines use links to go through all the sites on the web. If there dofollow link in your blog, and the dofollow link find by any bot, it follows it and lands on another page. This is the way only bots come to know about your websites and helps to index or cache them and display it in search results. I like blog commenting as a link building strategy.
NoFollow is used as the value in rel attribute of HTML anchor (<a>) tag. For example:
<a href=”http://www.example.com/” rel=”nofollow”>Link text</a>
By default a link is mark as a doFollow link. To mark a link as doFollow we don’t need to mention about doFollow.
A “no follow” link gives Google and other major search engines specific instructions. When a “no follow” code is part of a link, the theory goes that Google will NOT follow the link while crawling your site. In this case the link will NOT included when calculating Page Rank for your web page. As a Search Engine Optimizer often get requests to find only “do follow” links for our clients. Nofollow is ignored most time.
Check what said Major Search Engines: (Source: http://en.wikipedia.org/wiki/Nofollow)
While all engines that use the nofollow value exclude links that use it from their ranking calculation, the details about the exact interpretation of it vary from search engine to search engine:
- Google states that their engine takes “nofollow” literally and does not “follow” the link at all. However, experiments conducted by SEOs show conflicting results. These studies reveal that Google does follow the link, but it does not index the linked-to page, unless it was in Google’s index already for other reasons (such as other, non-nofollow links that point to the page).
- Yahoo! “follows it”, but excludes it from their ranking calculation.
- Bing respects “nofollow” as regards not counting the link in their ranking, but it is not proven whether or not Bing follows the link.
- Ask.com also respects the attribute.
So after above points we can say nofollow links also contribute value to a site’s rank in all three major search engines. Any links that happen to be nofollow continue to add to a site’s overall link profile and ability to rank for it’s keyphrase.
No follow links were first developed by Google as a way to control spam links on blogs . Search engine optimization professionals started using the nofollow attribute to control the flow of PageRank within a website, but Google since corrected this rules and any link with a nofollow attribute decreases the PageRank that the page can pass on. This practice is known as “PageRank sculpting“.