Big Data Systems encompass massive challenges related to data diversity, storage mechanisms, and requirements of massive computational power. Further, capabilities of big data systems also vary with respect to the type of problems. For instance, distributed memory systems are considered ill-suited for iterative algorithms. Similarly, variations in big data systems also exist related to consistency and fault tolerance. The purpose of this book is to provide a detailed overview of big data systems. The book adopts a challenge-centric approach in which platforms are evaluated based on their capabilities to solve specific challenges.