Twitter is a popular microblogging platform used by millions of people around the world to share their thoughts or communicate about current events. Because of Twitter's relative ease of access for both posting and reading, especially from mobile devices, it has emerged as an important platform for sharing information during public events, such as political crises and protests, or to track the emergence of an issue in the public consciousness. Saved tweets become a sort of time capsule, providing a wealth of insight into public sentiment at the time of the event. Frozen in time, the tweets themselves are unaffected by memory lapses or subsequent reversals in public opinion. Scholars and media experts can collect and study these topical tweet archives to attempt to learn more about what the public opinion was at the time, or about how information traveled, or even about what happened in an event, when it happened, and why.

Many people...