Twitter is an amazing real-time information dissemination platform. Weve seen events of historical importance such as the Arab Spring unfold via Tweets. We even know that Twitter is faster than earthquakes! However, can we more scientifically characterize the real-time nature of Twitter?One way to measure the dynamics of a content system is to test how quickly the distribution of terms and phrases appearing in it changes. A recent study weve done does exactly this: looking at terms and phrases in Tweets and in real-time search queries, we see that the most frequent terms in one hour or day tend to be very different from those in the next — significantly more so than in other content on the web. Informally, we call this phenomenon churn.