Hidden text is coded content invisible to visitors of a website but readable by search engine spiders. It is used to raise the keyword density of a website without affecting its visual appearance. Hidden Text is recognized as a black hat seo technique, also known as a spam tactic by nearly all major search engines because it presents your site as untrustworthy since your information is viewed differently by your visitors and by search engines.
Make sure to avoid hidden or unusually tiny text to evade any penalty. Instead, you can create relevant and keyword rich Title tags for text and ALT tags for images to increase the keyword density of your website. Furthermore, use HTML links on your homepage and utilize important keywords and descriptions in your content through Meta tags and position them near the top of your pages. This will help your webpage become more keyword rich and avoid penalties at the same time.