With 241 million users, Twitter represents a relatively small slice of the human population, especially considering that only a small proportion of Twitter users send the bulk of the tweets. But that small pool of people is disproportionately loud, and, like it or not, Twitter and its users are a force.
The service is affecting how we consume, report, share and discuss the news, and affecting how people forge and congregate around facets of their identity. Though the same can be said of all social media, Twitter's default—public and open accounts—means that it does this a little differently. It's easier for others to look in and watch conversations take shape. And, for scientists, Twitter's public nature means that tweets are relatively easy to study.
For years scientists have been studying people's tweets: they've tracked how misinformation spread during the wake of the Boston bombings; they've used people's reports of shaking to detect earthquakes; they've tried, with mixed success, to use it to track the spread of the flu.
Unfortunately, researchers' access to Twitter's archives has been limited, says Melinda Wenner Moyer for Scientific American: scientists can only pull and analyze around 1 percent of the tweets. That's changing, though, says Moyer: Twitter is opening up its archives—every tweet all the way back to the service's inception in 2006 will be available for research.