Recent developments in the web, social media, sensors, and mobile devices have resulted in the explosion of data set sizes and the emergence of big data. It has applications in retail, healthcare, financial services, government, agriculture, and customer service, among other sectors. At the same time, organisations depend on the protection of users’ data, and the scale of these data environments makes effective analysis and protection more difficult with traditional techniques. This review examines the main security and privacy issues in big data, beginning with its characteristics and value before discussing the major challenges and possible directions for future research.