Invisible text is content on a web site that is coded in a manner that makes it invisible to human visitors, but readable by search engine spiders. This is done to artificially inflate the keyword density of a web site without affecting the visual appearance of it. Hidden text is a recognized spam tactic and all major search engines recognize and penalize sites using this tactic.

There is also the technique of placing text on a page in a small font size. Pages that are predominantly heavy in tiny text may be considered as spam or may not be indexed. So try and avoid pages where the font size is predominantly smaller than normal.

Make sure that you’re not spamming the SEs by using keyword after keyword in a very small font size. A copyright notice or the contact information at the very bottom of the page in tiny text would be fine.

Search engines are unable to view graphics or distinguish text that might be contained within images. For this reason, most SEs will read the content of the image ALT tags to determine the purpose of a graphic. The key to increase the keyword density of your site is to craft relevant, yet keyword rich ALT tags for the images on your web site. It’s also important not to go overboard in using these tags as part of your SEO campaign. Most engines will not give this text any more weight than the text within the body of your site.

Keyword stuffing and spamming

Important keywords and descriptions should be used in your content in visible Meta tags and you should choose the words carefully and position them near the top and have proper frequency for such words. However don’t do it too much as Keyword stuffing or spamming is an unethical practice and the search engine algorithms can spot this, some may even penalize it.

Re-direct pages

Sometimes pages have a Meta refresh tag that redirects any visitor automatically to another page. Some search engines refuse to index a page that has a high refresh rate. The meta refresh tag however does not affect Google.

Image maps without alt text

Avoid image maps without text or with links. Image maps should have alt text and the home page should not have images as links. Instead HTML links should be used. This is because search engines would not read image links and the linked pages may not get crawled.