A meta tag in the HTML code of a web page that tells search engines to disregard the page. On pages such as blog posts that invite user comments, a nofollow link protects you from search engines ranking your page based on user comments you can’t control. Let’s say some users comment on your blog post to promote their own products and stuff your comments with keywords. You can use a nofollow tag to avoid search penalties.

Effective Email Marketing
Email marketing is quickly becoming one of the most popular forms of Internet advertising. This is because there are many distinct advantages to the concept