Dofollow links are an HTML attribute that is used to allow search bots to follow the links. If a webmaster is link to your site with dofollow link, search engine bots and people can follow you. They pass on link juice and really benefit your website to get a high Page Rank.
Google takes notes of Dofollow links and figures how many users are linking to your page in order to get how really good the page is. The more Dofollow links you have, the more points you will get. The best way to give the follow link is to use the keyword as the anchor text. This means when you are linking to any website or page, use the targeted keyword as anchor text.