Friday, 13 March 2009

Word clouds versus tag clouds

The word ‘cloud’ is increasingly used in the context of Web 2.0, perhaps because so much of it seems ‘blue sky’ to a lot of people. However, a cloud in the context of tagging has nothing to do with cloud computing. It refers to a visual representation of terms weighted by frequency – in most cases this weighting is indicated by size, as in the images provided.

Take for a timely example; the site of a U.S. Presidential rhetoric project. When the page loads, you are presented with a cloud displaying the words most frequently used in the 2007 State of the Union speech. Obama’s inaugural speech has not yet been loaded there, but you can pull the slider back through time from the pyrocumulus of Bush’s address, hell-bent on the themes of ‘Iraq’ and ‘terrorists’, to the noctilucent beginnings of the United States with John Adams’ ‘Foundation of Government’ speech, in which only the hopeful words ‘assembly’ and ‘constitution’ loom large.

The site calls itself a ‘tag cloud’ but it’s more accurately a bunch of ‘word clouds’ and a timeline. Tags are a form of metadata and as such used to describe the content of text, not necessarily act as a representative sample of that content. For example, you might upload the Bush speech to a blog, tag it with all the words featured in the word cloud we have seen and thereby have your tag cloud and the word cloud coincide. But you could also, if you wanted, add the tags ‘warmongering’, ‘incompetent’ or even the multi-word ‘worst president in history’, which to my knowledge don’t appear in the speech at all.

Word clouds also tend to be static – you input the text and get your cloud – whereas tag clouds tend to be dynamic, checking how many items (be they blog posts or bookmarks) have a particular tag and then sizing them accordingly. The more you use a tag across several blog postings for example, the larger that term will grow in your tag cloud, giving visitors an easy overview of what the blog is about.

You can create your own word clouds (for free) perhaps as a resource for your students or for use in slideshow presentations by going to To see a tag cloud in action, go to my blog ( where you can also find links to the resources listed here and more.

No comments: