What is a do-follow backlink and No-follow backlink ?

What is a do-follow backlink and No-follow backlink  ?

Dofollow backlinks 

Dofollow backlinks pass the authority from the referring website while nofollow don't. 

descriptor of links describing that search engines crawl them 

Dofollow links allow to all search engines (google ,  yahoo , bing ) to follow them and reach our website. Giving us link juice and a backlink.

Nofollow backlink 

nofollow links do not pass PageRank they likely don't impact search engine rankings . Nofollowed links are hyperlinks with a rel=“nofollow” tag. These links do not influence the search engine rankings of the destination URL because Google does not transfer PageRank or anchor text across them . but some time more useful for traffic 

how to check backlink is Dofollow or nofollow backlink 

• Open your Chrome or browser
• Then rightlick in webpage 
• Open inspect element
• Once you do that, a window will show up on the right with the link HTML highlighted.
• Simply check to see if the rel=“nofollow” attribute .that mean your link is nofollow

Nofollow links are links with a rel=”nofollow” HTML tag applied to them.