2018 (MMXVIII) was a common year starting on Monday of the Gregorian calendar, the 2018th year of the Common Era (CE) and Anno Domini (AD) designations, the 18th year of the 3rd millennium and the 21st century, and the 9th year of the 2010s decade. 2018 was designated as the third International Year of the Reef by the International Coral Reef Initiative.