This Study Companion is a comprehensive self-study guide for the requirements of the 2021 International Fuel Gas Code. It addresses gas appliance and equipment installation, fuel gas piping systems, combustion and ventilation air, chimneys and vents, gaseous hydrogen systems, and more. The Companion's 10 study sessions provide practical learning assignments and contain specific learning objectives, applicable code text and commentary, and a list of questions summarizing key points for study. A 25-question quiz at the end of each study session allows users to test their knowledge of the material. An answer key indicates the correct response and reference for each of the 250 total questions.