This document provides an introduction to data science, including an overview of big data challenges, the field of data science, and the role of data scientists. It defines big data as data that is expensive to manage and difficult to extract value from due to issues of volume, velocity, variety and complexity. It also outlines different types of data including relational, text, semi-structured, graph and streaming data. The document discusses how data science uses theories and techniques from fields like computer science, mathematics and statistics to analyze large amounts of data and help decision makers. It notes the growing demand for data scientists and provides some real-life examples of data science applications.