This document discusses intelligent transportation systems (ITS). It provides an overview of ITS taxonomy, including advanced traffic management systems, advanced traveler information systems, advanced vehicle control systems, commercial vehicle operations, and advanced public transportation systems. It also describes the schematic workings of traffic management centers, which acquire data from sensors and GPS to monitor road conditions and provide real-time information to travelers via various communication tools. The goals of implementing ITS are to automate data collection, enable fast communication of information, help analyze traffic data, and reliably inform the public and travelers.