suddently think of this today, by using the meta index nofollow, this can prevent the bot from crawling to external site, and thus preventing links to unrelevant site, and to bad neighbourhood as well. is there any proof that this helps page ranking?

Not linking out or using nofollow doesn't improve you ranking.
Why would google think it's bad to link out?

If you do have links to bad neighbourhoods you should remove those links, Not just prevent bots following them.

I agree. If you really care about search engine traffic, and especially Google, remove links to bad neighborhoods.

From what I understand of "nofollow", it does several things.

1. prevents bots from following links to information you don't want on the SE's.
2. preserves your PR on Google by preventing the bot from following the link (a little complicated, trust me =) ).
3. prevents bots from following links to internal pages to prevent duplicate content from being found, ie; a post on the front page of your blog being the same as the post's individual page.

Now I'm lumping the "nofollow" meta with the "rel="nofollow" in the anchor link, but the way I see it the work similar.

I'm sure someone else has a better explanation,

Don

Charles linking out to other sites can actually help your site. Linking to other sites on your topic helps place your site as on the same subject and helps establish topical authority.

If you don't want search engines to see links out to unrelated sites don't link to unrelated sites.

If you run a blog or something else which has user generated content you may want to add rel="nofollow" to the links since you don't have as much control over those links.

And if you add nofollow to all your links why would anyone link to you?

The other angle behind using "nofollow" in your meta tag is that ALL of your links, internal and external, won't be followed. Is that what you really want? Doesn't sound like it.

If these neighbourhoods are so bad, they won't send you anything you can use, so why link to them as others have pointed out? It's just a wasted link.

Originally Posted by vangogh

Charles linking out to other sites can actually help your site. Linking to other sites on your topic helps place your site as on the same subject and helps establish topical authority.

Interesting. I link out when it's appropriate ... I wrote an article on B/W photography that links out to Ansel Adams, Sebastiao Salgado, and so on. All of my links fit well within the context of what I'm writing about, and have a lot of great info that I'm not going to include on my page. It's stuff people interested in a topic will want to know more about.

Never considered that this would have any effect on search rankings. Interestingly, I can't find this page in the top 20 without using my name in the query. It might get 500 to 600 visitors a month.

I wouldn't start linking out to 'authority' sites just to get a ranking boost. Whether or not this helps ranking is a contentious issue. I wouldn't even think about SEO when linking out.

I agree gringo and didn't mean to imply everyone should start linking out looking for an seo boost. I link out on my site when it makes sense to link out. If I reference a source that I'm writing about with more or different information than what I'm writing about it might get a link.

I link externally when I think it will benefit visitors to my site.

I just wanted to point out reasons why you shouldn't be afraid to link to another site.

Forrest while linking out can help it's by no means the kind of thing that will automatically rank a page. Your page may have moved from 500 to 480 with the links, but it takes more to move it into the top 20.

The main thing is not to be afraid to link to other sites. If it makes sense and benefits your visitors to link to a page on another site it's a good thing to link to that page. That would be true even if there were no such thing as a search engine.

Dont know much but i know linking to site with no follow tag will never help you in increasing the SERP.So dont go for it. It is totally wasting of time.