Nofollow link is exactly vice-versa of dofollow link. These are non-crawling link which are not passed by search engines bot and hence can
for differentiate dofollow nofollow there are so many add-ons available in market I think you will try nodofollow add-ons
We have discussed same thing here. check out . it will help you . http://forums.digitalpoint.com/showthread.php?t=2246063
Do follow is the link followed by search engines and no follow is the link that not followed by search engines. Do follow links helps to increase ranking and visitors and other side no follow only gives visitors.
Nofollow links attributes do not allow search engine optimization bots to follow link.While Dofollow links allow search engines (all search engines) to follow them and arrive at our website. Thanks, Raj Tent | Raj Tents
Google count the only do-follow links as best for ranking of any keyword because those websites are giving back links to get ranking in search engine. Google not count no-follow links as back links for get ranking in search engine.
All links are Dofollow already but if you want your links not crawl by search engine bots then you Nofollow links attributes in <a> tag