Tag Cloud is a stylized way of visually representing occurrences of words used to described tags. Tags are usually single words, and the importance of each tag is shown with font size or color. Tag clouds on a high-profile website were on the photo sharing site Flickr, created by Flickr co-founder and interaction designer Stewart Butterfield. That implementation was based on Jim Flanagan’s Search Referral Zeitgeist, a visualization of Web site referrers. A second generation of software development discovered a wider diversity of uses for tag clouds as a basic visualization method for text data.