What is the name of the desert that covers parts of Algeria, Chad, Egypt, Libya, Mali, Mauritania, Morocco, Niger, and Tunisia?

Which desert is located in the southwestern United States and northwestern Mexico? What is the largest cold desert in the world? Which desert is the largest continuous sand desert in the world? In which continent is the Patagonia Desert located? What is the name of the desert that covers about 270,000 square kilometers in Western Australia? In which country is the Atacama Desert located? What is the name of the desert that covers parts of South Africa, Namibia, and Botswana? In which continent is the Arabian Desert located?