Hidden text refers to any textual content on a webpage that is not visible to users but can be read by search engine crawlers. This is often done by making the text the same color as the background, using CSS to position text off-screen, or setting the font size to zero.

In relation to SEO, hidden text is considered a black hat technique used to manipulate search rankings by stuffing pages with keywords or irrelevant content.

Search engines like Google view hidden text as deceptive and may penalize or ban websites that engage in this practice.

Legitimate, visible content relevant to users is the recommended approach for SEO.