Quick Answer: 2021 was a common year starting on Friday of the Gregorian calendar, the 2021st year of the Common Era and Anno Domini designations, the 21st year of the 3rd millennium and the 21st century, and the 2nd year of the 2020s decade. Like the year 2020, 2021 saw the year by the COVID-19 pandemic ongoing, due to the emergence of multiple COVID-19 variants. The major global rollout of COVID-19 vaccines, which began at the end of 2020, continued in 2021. Most major events scheduled for 2020 that were postponed due to the pandemic were hosted in 2021, including the 26th United Nations Climate Change Conference, Expo 2020, and sporting events such as UEFA Euro 2020, the 2020 Summer Olympics and Paralympics, as well as the 2021 Copa América. 2021 additionally witnessed numerous advancements in space exploration, particularly by the United Arab Emirates, NASA and SpaceX, including the launch of the James Webb Space Telescope.