Algeria (Arabic: الجزائر ‎ al-Jazā'ir), officially People's Democratic Republic of Algeria, is a country in North Africa on the Mediterranean coast.Its capital and most populous city is Algiers.With an area of 2,381,741 square kilometres (919,595 sq mi), Algeria is the tenth-largest country in the world, and the largest in Africa and the Arab world.ts capital and most populous city is Algiers. With an area of 2,381,741 square kilometres (919,595 sq mi), Algeria is the tenth-largest country in the world, and the largest in Africa and the Arab world.