The major search engines (Google, MSN, and Yahoo!) use a common HTML attribute for adjusting SEO rankings. When these search engines see the No Follow attribute in a hyperlink, they will exclude this link from its indexing and statistics gathering. Contrary to popular opinion, the No Follow attribute will not prevent robots from following the link, its mainly used to prevent search engine from adjusting a web siteâ€™s rank with a link that the owner does not want referenced.
You can make any link No Follow by inserting the attribute in the anchor tag:
<a href="www.website.com" rel="nofollow">website</a>
If you want to make all links No Follow on a page, then use the attribute in a meta tag in the <head></head> section of a web site:
<meta name="robots" content="noindex, nofollow">