The Mesolithic, or Middle Stone Age (from the Greek "mesos", 'middle', and "lithos", 'stone'), was a period in the development of human technology between the Palaeolithic and Neolithic periods of the Stone Age.

The Mesolithic period began at the end of the Pleistocene epoch, some 10,000 BP, and ended with the introduction of agriculture, the date of which varied by geographic region. In some areas, such as the Near East, agriculture was already underway by the end of the Pleistocene, and there the Mesolithic is short and poorly defined. In areas with limited glacial impact, the term "Epipalaeolithic" is sometimes preferred.

Regions that experienced greater environmental effects as the last ice age ended have a much more evident Mesolithic era, lasting millennia. In Northern Europe, societies were able to live well on rich food supplies from the marshlands fostered by the warmer climate. Such conditions produced distinctive human behaviours that are preserved in the material record, such as the Maglemosian and Azilian cultures. These conditions also delayed the coming of the Neolithic until as late as 4000 BCE (6,000 BP) in northern Europe.

Remains from this period are few and far between, often limited to middens. In forested areas, the first signs of deforestation have been found, although this would only begin in earnest during the Neolithic, when more space was needed for agriculture.

The Mesolithic is characterized in most areas by small composite flint tools: microliths and microburins. Fishing tackle, stone adzes and wooden objects, e.g. canoes and bows, have been found at some sites. These technologies first occur in Africa, associated with the Azilian cultures, before spreading to Europe through the Ibero-Maurusian culture of Northern Africa and the Kebaran culture of the Levant. However, independent discovery is not ruled out.

Neolithic
Iron Age
Mesolithic
Bronze Age