The Sahara (Arabic: الصحراء الكبرى‎, Aṣ-Ṣaḥrā´ al-Kubrā, "The Great Desert") is the world's largest hot desert and third largest desert, after Antarctica and Arctic. At over 9,400,000 square kilometres (3,600,000 sq mi), it covers most of Northern Africa, making it almost as large as China or the United States. The Sahara stretches from the Red Sea, including parts of the Mediterranean coasts, to the outskirts of the Atlantic Ocean. To the south, it is delimited by the Sahel, a belt of semi-arid tropical savanna that composes the northern region of central and western Sub-Saharan Africa.

Some of the sand dunes can reach 180 metres (590 ft) in height. The name comes from the Arabic word for desert: (صَحراء ṣaḥrāʾ [sˤɑħrɑːʔ] ( listen)).