Author's Note: This article is part of a series detailing specific spam warnings that webmasters might find displayed in Google Webmaster Tools manual action viewer, the types of things that are flagging each warning, and what webmasters should do to fix it to see the warning removed.
Hidden text and keyword stuffing isn't as common today of it once was, but Google is still warning webmasters to avoid.
When you mention hidden text and keyword stuffing, people often think of the 50 lines long text white text on white background in the footer of a webpage. It essentially means placing text on a webpage but for search engines only, not the user.
This was used extensively a decade ago, although it has evolved to include things such as using CSS to hide it off the page, to place it underneath another element already on the page, or to just set the text of hidden.
Keyword stuffing is putting a keyword phrase, or several, multiple times within a webpage, to the extent where whatever is on the page doesn't even make much sense because of the repetitive keywords. This is done so that the keywords are visible to search engine, with the idea that it will help it rank better in Google.
Cutts very specifically brought up the point that many spinner programs – programs that will essentially take content already available on the web and “spin it” to create new content – often don't pass the keyword spamming test. The output is often gibberish and nonsensical.
Most keyword stuffing examples are very obvious. While it is good to have your keywords within your text on the page, you can go overboard quite easily. If you want a quick method on how to check to see if your webpage is a little bit too keyword happy, read your text out loud, as it will often sound very unnatural. If it sounds fine to you or to those you read it too, it should be fine.
Why is this a problem? When users search for certain keywords and end up on your site, they want to see those keywords on the page in a useful format. They don't want to end up there due to hidden text located in the footer. Hidden text and keyword stuffing often make for a very poor user experience for it the user coming in from Google, which is why Google take such a stance on the issue
If you get the warning for hidden text or keyword stuffing, the solution is pretty easy: simply remove it. This type of SEO is still utilized today by some of the scammier SEO companies, so if you are unsure where it is, start looking at your actual source code find it, generally either close to the top or close to the bottom of the code.
Cutts said that occasionally it is a case of hacked site – hidden text and keyword stuffing is most common on WordPress sites, so if you get the warning on a WordPress site, your first thing to do should be to check whether you've been hacked, and if so, upgrade your WordPress and all your plug-ins, and then begin your cleanup process.
Google advises you should document your cleanup process. So document what you found, and how you fixed it, and the dates you did. Cutts said you should also include why it happened, whether it was a rogue SEO or a CMS system gone wild, and explain why you believe it won't happen again.