Word clouds are a simple type of visualization which use font size of a word to represent that word's frequency in a body of text. They're kind of gimmicky, and don't offer any deep analysis of the text. They could be useful for understanding what someone might be saying in a series of short messages, such as texting, Twitter or Facebook posts. For example, a data story word cloud of someone's tweets in a given year vs. another. Play with the example below, and you'll find them kind of fun if nothing else. This example was built using the D3 word cloud plugin.