Hidden Text is one of the challenges faced by webmasters and search engines. Spammers continue to use hidden text to stuff keywords into their pages for purposes of artificially boosting their rankings. Search engines seek to figure out when spammers are doing this, and then then take appropriate action.
To start our look at hidden text, let's examine Google's Webmaster Guidelines for hidden text, to see the bottom line:
If your site is perceived to contain hidden text and links that are deceptive in intent, your site may be removed from the Google index, and will not appear in search results pages
A Few Ways to Create Hidden Text
· Make your text and background colors identical (or virtually identical) - this is the original method used by spammers for creating hidden text. It's easy to detect, and I am not aware of any legitimate use for this technique.
· Set the font size for text to 0, or to a negative number. This is also easy to detect, and I can't think of any legit use for it either.