This document discusses Yammer and its API. It introduces Yammer as an enterprise microblogging tool that is similar to but different from Twitter. It then explains that the Yammer API uses HTTP(S) and returns XML or JSON formatted contents to allow accessing Yammer programmatically. It notes some of the capabilities of web APIs in general including their use on mobile phones and for mashups. The document encourages exploring new possibilities with the Yammer API.