This document provides an overview of big data, including its definition, characteristics, sources, tools, applications, risks, benefits and future. Big data is characterized by large volumes of data in various formats that are difficult to process using traditional data management and analysis systems. It is generated from sources like user interactions, sensors and systems logs. Tools like Hadoop and NoSQL databases enable storing, processing and analyzing big data. Organizations apply big data analytics to areas such as healthcare, retail and security. While big data poses privacy and management challenges, it also provides opportunities to gain insights and make improved decisions. The big data industry is growing rapidly and expected to be worth over $100 billion.