What is use of Nofollow in internal link, it is harmful of banificial for our site? Please Guide me...........
You shouldn't. If you're worried about leaking PR somewhere, make sure that page links to all the others and anything important. Things like privacy policies and contact forms can be included as part of other pages using the #links.
your internal pages get PR transfer form your main page so any page that is not important in terms of ranking, contact us page for example, you can use nofollow on those kind of links to avoid PR leak
There is absolutely nothing wrong with nofollow'ing links to pages on your site that you don't really care about ranking. For instance, links to a secure login page are typically worthless to have appear in the SERPs. Why should Googlebot waste time crawling that page? It won't login... You may not care whether your about-us or contact-us pages show up in the SERPs... or some privacy policy, terms of service, and disclosures pages. Nofollow them if you like. Matt Cutts has said repeatedly that it is ALWAYS perfectly acceptable to use nofollow on internal links such as these as well as when linking to external pages. He's stated there is NO penalty for misuse of nofollow. How the hell would you 'misuse' nofollow anyway? So I don't know why people get all bent out of shape about using them. At Pubcon the last two years, I bet I've heard 50 people ask him about nofollow. His response is always essentially feel free to use it as much or as little as you like... but your time could probably be better spent doing other things. PR scupting w/ nofollow is generally SEO fine tuning with small benefits, and most sites have much bigger SEO problems they could/should be dealing with than nofollowing 5 links on a page with 200 outbound links. The NY Times nofollows massive numbers of links (hundreds per pages) to direct the bots to various important parts of their sites... And they change literally hundreds of nofollows per page on many pages several times per day as the breaking news moves from one section of the site to another... They did a great session on it at Pubcon 2008. Finally, Google finally added a nofollow documentation page on their help center http://www.google.com/support/webmasters/bin/answer.py?hl=en&answer=96569 where they give a couple examples where one might want to use them. Note the paragraph from their help center on nofollow: Notice there is no notice that, "If you use it this way then that is a violation of Googles Webmaster Guidelines". They could care less.
Google recommends adding nofollow to internal links like login pages etc. So it's not a bad practice.
its a great practise, I've been doing this as long as I can remember, remember the less google leaves your home page, the stronger it is!
No follow is used to prevent the leaking of your PR and its quite beneficial for outbound links. In internal linking it is normally given to those pages which are not very much important like privacy policy, contact us for those u dont want the PR juice to leak...but such use of 'nofollow' may create orphaned pages in your root directory which is not good for overall crawlability of your site