Big data refers to extremely large datasets that are difficult to store, manage and analyze using traditional database tools. The volume of data in the world is growing exponentially and is projected to reach 35 zettabytes by 2020. Big data is important because it enables new forms of innovation and competition through deeper insights. Visual analytics is the use of interactive visual interfaces to synthesize and analyze large, complex datasets. It draws upon techniques from fields like statistics, machine learning and information visualization. Challenges include developing intelligent algorithms to combine human and machine analysis of large datasets and enabling the visualization of intermediate results from large-scale simulations and computations.