This document presents an overview of big data. It defines big data as large, diverse data that requires new techniques to manage and extract value from. It discusses the 3 V's of big data - volume, velocity and variety. Examples of big data sources include social media, sensors, photos and business transactions. Challenges of big data include storage, transfer, processing, privacy and data sharing. Past solutions discussed include data sharding, while modern solutions include Hadoop, MapReduce, HDFS and RDF.