“In the field of ‘big data’, Gartner identified five different types of data source used to ‘exploit big data’ in a company (Buytendijk et al., 2013): ‘Operational data comes from transaction systems, the monitoring of streaming data and sensor data; Dark data is data that you already own but don’t use: emails, contracts, written reports and so forth; Commercial data may be structured or unstructured, and is purchased from industry organisations, social media providers and so on; Social data comes from Twitter, Facebook and other interfaces; Public data can have numerous formats and topics, such as economic data, socio-demographic data and even weather data.’” Philipp Max Hartmann, Mohamed Zaki, Niels Feldmann, Andy Neely