2011 (MMXI) was a common year starting on Saturday of the Gregorian calendar, the 2011th year of the Common Era (CE) and Anno Domini (AD) designations, the 11th year of the 3rd millennium and the 21st century, and the 2nd year of the 2010s decade.

The most notable event of the year was the Arab Spring that involved the killing of Muammar Gaddafi in Libya as part of a series of protests and government overthrows that swept through the Middle East.

2011 was designated as:

• International Year of Forests
• International Year of Chemistry
• International Year for People of African Descent

In 2011, the nation of Samoa only had 364 days as it moved across the International Date Line skipping December 30, 2011; it is now 24 hours ahead of American Samoa.