This document provides an overview of advertising technology and programmatic advertising. It defines programmatic advertising as an automated, technology-driven method of buying, selling, and fulfilling digital ads that replaces traditional manual processes. It then summarizes key components of the programmatic advertising ecosystem like data management platforms (DMPs), supply-side platforms (SSPs), demand-side platforms (DSPs), and real-time bidding (RTB). The document aims to help readers understand the complex plumbing and players involved in modern programmatic advertising.