The Sahara desert, as defined by the World Wide Fund for Nature (WWF), includes the hyper-arid center of the Sahara, between latitudes 18° N and 30° N.[1] It is one of several desert and xeric shrubland ecoregions that cover the northern portion of the African continent.

The North Saharan steppe and woodlands receives more regular winter rainfall than the Sahara Desert ecoregion.

These Saharan mountains are home to two distinct ecoregions; the West Saharan montane xeric woodlands in the Ahaggar, Tassili n'Ajjer, Aïr, and other ranges in the western and central Sahara Desert and the Tibesti–Jebel Uweinat montane xeric woodlands in the Tibesti and Jebel Uweinat of the eastern Sahara.

The surface of the desert ranges from large areas of sand dunes (erg), to stone plateaus (hamadas), gravel plains (reg), dry valleys (wadis), and salt flats.

Some areas encompass vast underground aquifers, resulting in oases, while other regions severely lack water reserves.

More than half of the desert area is hyper-arid and virtually rainless, with an average annual precipitation below 50 millimetres (2.0 in) and many consecutive years may pass without any rainfall.

Local inhabitants protect themselves from the heat, the sunshine, the dry air, the high diurnal temperature ranges, and the sometimes dusty or sandy winds by covering their heads, such as the cheche garment worn by Tuareg.

[1] The most degradation is found in areas where there is water, such as aquifer oases or along the desert margins where some rain usually falls most years.