Why is "nofollow" used?

[backwow]

Some sites use nofollow attributes with some links.what's their purpose to use nofollow? What is the benefit they'll get?

[Kaiser]

Because if you feature low-quality (spammy) links on your site it can affect your rankings.

[rayter]

Putting nofollow attributes is a good strategy to prevent spammers from posting irrelevant comments to a site.

[bayoisa]

Nofollow links can be used for your site if you don't want pages crawled and indexed. This is applicable to irrelevant pages. For blogs and forums, nofollow can be used to prevent spam.

[aubreyrafaeli]

Some sites use nofollow attributes with some links.what's their purpose to use nofollow? What is the benefit they'll get?

Nofollow is an HTML attribute that instruct search engines spiders/crawlers to not follow (crawl) a particular web page.

Benefits? Well, I guess... its main benefit has something to do with the word "PRIVACY". Imagine this... if there will be no "nofollow" attribute, everything will be crawled... even the messages (PMs) in your forums accounts will be seen by other Internet users.

[chauhan]

Nofollow links can be used for your site if you don't want pages crawled and indexed. This is applicable to irrelevant pages. For blogs and forums, nofollow can be used to prevent spam.

For your kind information Nofollow links are crawled by Google but Google does not count that link for ranking purpose but for traffic purpose you can also do Nofollow comment.

[paulean]

This differs from the meaning of nofollow as used within a robots meta tag, which does tell a search engine: "Do not follow" ...and do follow are those which tells search engine robots to follow this hyperlink

[abbiabe]

Nofollow is an HTML quality value used to teach some search engines that a hyperlink should not power the link target's ranking in the search engine's index.

[Organs]

preventing spamming for sure. Now Google considers nofollow links as backlinks too, but they will not pass on any PR juice.

[andr77]

You are pretty right here, but still since it may bring you some traffic, then I think such links are of great use

[Blake]

I'm not so sure no follow work the same as do follow, though I heard some researches were made in this field and the results were positive.In any case it doesn't work for me as I expect it

[gina222114]

For some situation, there are some pages you don't wanna the searchengine crawled and indexed, you can use a Nofollow link to make them avoid the Crawler.

[comsdev]

nofollow attributes protect you site from spammers for brief detail visit
http://en.wikipedia.org/wiki/Nofollow

[vstrategy]

nofollow is an HTML attribute value used to instruct some search engines that a hyperlink should not influence the link target's ranking in the search engine's index. But the link can gain a traffic. That is the benefit of no-follow links.

[infoman66]

For ordinary people: nofollow attribute is used to disparage the link in the eyes crwlera. That link is regular, but Google does not take into account when ranking the site.
They are usually used on forums and blogs to prevent spam-promotion.