This document provides an overview of big data, including its definition, characteristics, sources, tools used, applications, risks and benefits. Big data is characterized by volume, velocity and variety of structured and unstructured data that is growing exponentially. It is generated from sources like mobile devices, sensors, social media and more. Tools like Hadoop, MapReduce and data analytics are used to extract value from big data. Potential applications include healthcare, security, manufacturing and more. Risks include privacy and scale, while benefits include improved decision making and new business opportunities. The big data industry is rapidly growing and transforming IT and business.