This document provides an introduction to terrorism. It describes the characteristics of terrorist operations as dynamic, instantaneous, and using detailed planning and surveillance. It identifies several Iraqi insurgent groups active in Iraq such as Al-Qaeda, Al-Faraq Brigades, and Al-Mahdi Army. It explores how foreign jihadists enter Iraq through Syria and Iran. It reviews lessons from past terrorist operations through examples of ambushes, assassinations, and improvised explosive devices. The objectives are to understand terrorist operations and groups in Iraq.