2008 (MMVIII) was a leap year starting on Tuesday of the Gregorian calendar, the 2008th year of the Common Era (CE) and Anno Domini (AD) designations, the 8th year of the 3rd millennium and the 21st century, and the 9th year of the 2000s decade.

2008 is designated as:

The Great Recession, a worldwide recession which began in 2007, continued through the entirety of 2008.

The world population on January 1, 2008, was estimated to be 6.801 billion people and increased to 6.888 billion people by January 1, 2009. An estimated 141.8 million births and 54.0 million deaths took place in 2008. The average global life expectancy was 69.3 years, an increase of 0.3 years from 2007. The estimated number of global refugees decreased from 11.4 million to 10.5 million by the end of the year. The largest sources of refugees were Afghanistan with 2.8 million people and Iraq with 1.9 million people.

There were 37 conflicts in 2008 that resulted in at least 25 fatalities, five of which resulted in at least 1,000 fatalities: the Iraqi insurgency, the Taliban insurgency, conflict with the Pakistani Taliban, Eelam War IV in Sri Lanka, and the Somali Civil War. A border conflict broke out for two days between Djibouti and Eritrea, ending with Eritrean occupation of the disputed area, Ras Doumeira. This was the first conflict in four years where two sovereign states fought each other directly. The Russo-Georgian War occurred in August when Georgia engaged in warfare with the breakaway state South Ossetia following a series of skirmishes. Russia backed South Ossetia and sent 10,000 soldiers into the fight, progressing further into Georgia until a ceasefire was established. Two separatist rebel groups escalated conflict in India: Dima Halam Daogah sought a Dimasa state and the United National Liberation Front sought a Manipuri state.

Peace talks were held between Uganda and the Lord's Resistance Army (LRA) to end the LRA's insurgency, but LRA leader Joseph Kony refused to attend a final peace agreement and government operations against the LRA resumed in December. Peace talks were also held for the Central African Bush War and the Somali Civil War, but rebels were unable to reach final agreements in these conflicts. The National Forces of Liberation resumed its insurgency in Burundi when peace talks collapsed in January, but a ceasefire was established in December. Progress was made toward peace in the First Ivorian Civil War with preparations to integrate the Forces Nouvelles de Côte d'Ivoire into the Ivorian military.