Google and other search engines want to see new fresh content and links on a regular basis and use crawler bots to search through all the keywords and content on your site. When a website is inputting hidden links, such as white text on a white background, the crawler bots will still crawl that text, but it is severely frowned upon by the search engines as black hat SEO techniques. After time, Google might even blacklist your site from their index because they feel you are not using honest SEO techniques. A hidden link is a link that might be in a paragraph that you are reading on the site, but does not clearly look like a link, and you might accidently click a word, and get redirected to a different site.
Here is a breakdown of why Hidden Links are a bad idea directly from Google.com's website:
Now, if you do choose to use hidden links or hidden text, this is of course is against the advise of LinkU, and we do not assist in setting up your site with hidden links or other black hat SEO techniques.