Sensitive personal details relating to almost 200 million US citizens have been accidentally exposed by a marketing firm contracted by the Republican National Committee. The 1.1 terabytes of data includes birthdates, home addresses, telephone numbers and political views of nearly 62% of the entire US population. The data was available on a publicly accessible Amazon cloud server. Anyone could access the data. The information seems to have been collected from a wide range of sources - from posts on controversial banned threads on the social network Reddit, to committees that raised funds for the Republican Party. The information was stored in spreadsheets uploaded to a server owned by Deep Root Analytics. It had last been updated in January. Although it is known that political parties routinely gather data on voters, this is the largest breach of electoral data in the US to date and privacy experts are concerned about the sheer scale of the data gathered. This is not just sensitive, it's intimate information, predictions about people's behaviour, opinions and beliefs that people have never decided to disclose to anyone," [said] Privacy International's policy officer Frederike Kaltheuner. However, the issue of data collection and using computer models to predict voter behaviour is not just limited to marketing firms - Privacy International says that the entire online advertising ecosystem operates in the same way.