A while back, I promised to write about tag clouds. I’m a man of my word, and I apologize for the delay in getting to this promise.
First, let’s define tag clouds. A tag cloud is a visual depiction of a set of words or phrases that characterize a set of documents. While “tag” suggests that the words and phrases are user-generated, the contents of tag clouds are often supplied by authors or even automatically extracted. Typically, tag clouds order tags alphabetically and use the size (or some similar typographical aspect) of a tag to indicate its frequency or relevance to the document set.
Tag clouds have been derided as “the mullets of Web 2.0” (I believe the original “mullet” critic was Jeffrey Zeldman). As someone who at least finds himself advising clients about how to improve user experience, I have seen companies clamor for tag clouds without necessarily thinking through how users would benefit from them. Indeed, while a picture may be worth a thousand words, a tag cloud may simply look like a thousand words.
I know that both Red Sox and Yankees fans read this blog, so I won’t take sides on the accuracy of the Mitchell Report, But the change in the tag cloud clearly and concisely shows how the news about Roger Clemens changed when that report came out.
Unfortunately, tag clouds that offer insight are the exception, rather than the rule. Part of the problem is that tag clouds are only as good as the tags they depict: garbage in, garbage out. Tag clouds can also be so large and heterogeneous. Ryan Turner cites Flickr as such an example in his post, “Tag Clouds Are Bad (Usually)“:
As Greg recently blogged, tag clouds generated by social tagging systems can be worse than unhelpful; they can be actively misleading. Since tag clouds often occupy prime real estate on web site, they are a natural target for what Gartner analyst Whit Andrews calls “denial of insight” attacks.
In summary, tag clouds are a too-often abused but sometimes useful means to communicate information about a set of documents. But sites need to avoid presenting tag clouds simply expose the poverty of their tagging.
Also, while tag clouds may be an appropriate visualization for summarizing of a set of documents, they may not be the best means of presenting users with options for refning it. My colleagues and I discuss this problem in our upcoming HCIR presentation, and I’ll blog about it when I get back from the workshop.