Keyword stuffing is a technique that had been in use in the old days when the number of keywords on a page affected the ranking significantly, by means of which keywords would be hidden all over a page in a way that is invisible to users. Today, however, this method is basically useless and easily detected by the algorithms that become more and more sophisticated with each update. Websites that are detected to use this method will surely be penalized by search engines. This method, in which keywords with the same color as the background would be meaninglessly scattered all over the page, is one of the oldest black hat SEO tricks in the book.