We are in the big data era and data systems sit in the critical path of everything we do. We are going through major transformations in businesses, sciences, as well as everyday life—collecting and analyzing data changes everything and data systems provide the means to store and analyze a massive amount of data. This course is a comprehensive introduction to modern data systems. The primary focus is on modern trends that are shaping the data management industry right now such as column-store and hybrid systems, shared nothing architectures, cache-conscious algorithms, hardware/software co-design, main memory systems, adaptive indexing, stream processing, scientific data management, and key-value stores. We also study the history of data systems, and traditional and seminal concepts and ideas such as the relational model, row-store database systems, optimization, indexing, concurrency control, recovery, and SQL. In this way, we discuss both how data systems evolved over the years and why, as well as how these concepts apply today and how data systems might evolve in the future. We focus on understanding concepts and trends rather than specific techniques that will soon be outdated.