This document provides an overview of big data and related technologies. It defines big data as large amounts of data from various sources, including sensors, social media, purchases, and mobile devices. Hadoop and MapReduce are introduced as frameworks for distributed storage and processing of large datasets across clusters of servers. Key-value database Hypertable is also summarized as an open source alternative to Bigtable. The advantages of big data systems include flexibility, scalability, efficiency, and failure resistance through data replication.