[Alexa]

  "The eyes of Google, Yahoo, Bing..."  Cool!

[kgharshith]

Dofollow: The search engine spam indexing and to improve the search engine results. Only Dofollow links pass link juice to the linked webpage and influence the target’s page rank.
Nofollow: Nofollow means probably it’s a link is set as nofollow, it means Google bot won’t crawl the link and won’t pass any link juice.

[mohinischaudhari14]

Links that points to the another site are called do follow links.These links are helpful to increase page rank in search engines.

No follow links does not point to another site. These links are not helpful to increase page rank in search engines.

[SEOKavya]

In dofollow, crawling a website through google bots external links passed to the other links. on the other hand in nofollow, will not get deeper into crawling and no link juice is passed.