Chapter 1: An Introduction to COS 1.1 Overview 1.2 Observing with COS 1.2.1 Target Acquisitions 1.2.2 Observing Modes: Spectroscopic and Imaging 1.2.3 Observing Modes: TIME-TAG and ACCUM 1.2.4 Typical Observing Sequences 1.3 COS Quick Reference Guide 1.4 COS FAQ 1.5 Purpose of this Handbook 1.5.1 Document Conventions