With the 'Fit for 55' package, the EU's energy and climate policy instruments were aligned with the new climate target for 2030 (to reduce emissions by 55 % compared to 1990). One main feature of the Fit for 55 package is the strengthening of the European Emissions Trading System (EU ETS). This factsheet outlines the key aspects for the existing European Emissions Trading System for stationary installations and aviation (EU ETS 1), which will be extended to include maritime transport from 2024. In addition, changes to the associated Market Stability Reserve (MSR 1) are presented. A separate factsheet has been prepared on the creation of a new emissions trading system, in particular for buildings and road transport (EU ETS 2).