This Outlook is a modelling effort that analyses possible transformation pathways required to achieve net-zero GHG emissions in Canada, with a special focus on the energy system. Produced by independent researchers, this Canadian Energy Outlook 2021 (hereafter the CEO2021) builds on extensive techno-economic modelling to analyze the trends occurring across the country, the possible transformation of the energy sector over the next decades, the political choices that need to be made to reach national objectives, and the considerable gap between promises and targets. This analysis helps contrast the projected evolution of the energy system and GHG emissions with the measures implemented, to assess their coherence. The hypotheses and limits underlying this work, along with a brief discussion of the recent evolution of Canada’s energy sector, form the core of this introductory chapter.