<a href="www.example.com" rel="no follow" target="_blank"></a>
Anybody tell me the real use of nofollow and blank ?
"nofollow" tells search engines not to follow the link. This article gives examples of where and why you might want to use that: https://support.google.com/webmasters/answer/96569?hl=en
(If you want to exclude an entire page or directory from being indexed, you should use a robots.txt file.)
target="_blank" forces the link to open in a new window, which has long been considered bad practice: