A hunter-gatherer society is one whose primary subsistence method involves the direct procurement of edible plants and animals from the wild, foraging and hunting without significant recourse to the domestication of either. The demarcation between hunter-gatherers and other societies which rely more upon domestication (see agriculture and pastoralism and neolithic revolution) is not a clear-cut one, as many contemporary societies use a combination of both strategies to obtain the foodstuffs required to sustain themselves.

Hunting and gathering was presumably the only subsistence strategy employed by human societies for more than two million years, until the end of the Mesolithic period. The transition into the subsequent Neolithic period is chiefly defined by the unprecedented development of nascent agricultural practices. Agriculture originated and spread in several different areas including the Middle East, Asia, Mesoamerica, and the Andes beginning as early as 12,000 years ago. Many groups continued their hunter-gatherer ways of life, although their numbers have perpetually declined partly as a result of pressure from growing agricultural and pastoral communities. Areas which were formerly unrestricted to hunter-gatherers were, and continue to be encroached upon by the settlements of agriculturalists. In the resulting competition for land use, hunter-gatherer societies either adopted these practices or moved to other areas. Jared Diamond has also blamed a decline in the availability of wild foods, particularly animal resources. In North and South America, for example, most large mammal species had been hunted to extinction by the end of the Pleistocene.

As the number and size of many agricultural societies increased, they expanded into lands traditionally used by hunter-gatherers. This process of agriculture-driven expansion soon led to the development of complex forms of government in agricultural centers such as the Fertile Crescent, Ancient India, Ancient China, Olmec, and Norte Chico; and set in motion the impetus for further expansion through warfare and colonization.

As a result of the now near-universal human reliance upon agriculture, the few contemporary hunter-gatherer cultures usually live in areas seen as undesirable for agricultural use.