How to avoid some pages from being indexed by search engines?

There is rel="nofollow" but I am not sure about this if it prevents indexing. What do you say? Any ideas?

UPDATE

Sorry I wasn't very clear. There a page a.php, and it has links b.php, c.php, d.php and some other text content. The link to b.php is only relevant if the u开发者_开发技巧sers are on a.php, and doesn't really returns any output. Its not relevant if somebody goes directly on this b.php from yahoo/google search results.

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<META NAME="ROBOTS" CONTENT="NOINDEX, NOFOLLOW">

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You can update the robots.txt file specifying which URLS not to index or make sure that they are not in your sitemap.xml file

http://www.robotstxt.org/