Database Systems teaches the inner workings of data management systems. Focus areas include organizational data structures (physical layouts, indexes, materialized views), data processing algorithms (join, sort), query optimization (relational algebra equivalences, query planning, cost modeling), transactional semantics (X-serializability, locking, OCC, MVCC), and recovery (WAL, Undo Logging, ARIES). The course involves a term-long project where students build a query processing system.