Data science involves collecting, analyzing, and preserving large datasets to extract knowledge and make predictions. It differs from traditional disciplines by dealing with heterogeneous, unstructured data from complex networks. A data scientist requires math, computing, communication skills, and the ability to ask the right questions. Libraries are well-positioned to offer various data services including data discovery, consulting, mining, integration, and curation to support research and decision-making. Practicing data science in libraries requires vision, risk-taking, data science knowledge, careful planning, and collaboration.