Algeria, officially the People's Democratic Republic of Algeria, is a country in the Maghreb region of North Africa. It is bordered to the northeast by Tunisia; to the east by Libya; to the southeast by Niger; to the southwest by Mali, Mauritania, and Western Sahara; to the west by Morocco; and to the north by the Mediterranean Sea. The capital and largest city is Algiers, located in the far north on the Mediterranean coast.

Inhabited since prehistory, Algeria has been at the crossroads of numerous cultures and civilisations for millennia, including the Phoenicians, Numidians, Romans, Vandals, and Byzantine Greeks. Its modern identity is rooted in centuries of Arab Muslim migration since the seventh century and the subsequent Arabisation of indigenous Berber populations. Following a succession of Islamic Arab and Berber dynasties between the eighth and 15th centuries, the Regency of Algiers was established in 1516 as a largely independent tributary state of the Ottoman Empire. After nearly three centuries as a major power in the Mediterranean, the country was invaded by France in 1830 and formally annexed in 1848, though it was not fully conquered and pacified until 1903. French rule brought mass European settlement that displaced the local population, which was reduced by up to one-third due to warfare, disease, and starvation. The Sétif and Guelma massacre in 1945 catalysed local resistance that culminated in the outbreak of the Algerian War in 1954. Algeria gained independence in 1962. It descended into a bloody civil war from 1992 to 2002, remaining in an official state of emergency until the 2010–2012 Algerian protests during the Arab Spring.

Spanning 2,381,741 square kilometres (919,595 sq mi), Algeria is the world's tenth-largest country by area and the largest in Africa. It has a semi-arid climate, with the Sahara desert dominating most of the territory except for its fertile and mountainous north, where most of the population is concentrated. With a population of 47 million, Algeria is the tenth-most populous country in Africa, and the 32nd-most populous in the world. Algeria's official languages are Arabic and Tamazight; the vast majority of the population speak the Algerian dialect of Arabic. French is used in media, education, and certain administrative matters, but has no official status. Most Algerians are Arabs, with Berbers forming a sizeable minority. Sunni Islam is the official religion and practised by 99 percent of the population.

Algeria is a semi-presidential republic composed of 58 provinces (wilayas) and 1,541 communes. It is a regional power in North Africa and a middle power in global affairs. As of 2025, the country has the highest Human Development Index in continental Africa, and the third largest economy in Africa, due mostly to its large petroleum and natural gas reserves, which are the sixteenth and ninth largest in the world, respectively. Sonatrach, the national oil company, is the largest company in Africa and a major supplier of natural gas to Europe. In 2013, it had the largest miltiary budget in Africa. Algeria is a member of the African Union, the Arab League, the OIC, OPEC, the United Nations, and the Arab Maghreb Union, of which it is a founding member.

Different forms of the name Algeria include: Arabic: الجزائر, romanised: al-Jazāʾir, Algerian Arabic: دزاير, romanised: dzāyer, French: l'Algérie. The country's full name is officially the People's Democratic Republic of Algeria (Arabic: الجمهورية الجزائرية الديمقراطية الشعبية, romanised: al-Jumhūriyah al-Jazāʾiriyah ad-Dīmuqrāṭiyah ash‑Shaʿbiyah; French: République algérienne démocratique et populaire, abbr. RADP; Berber Tifinagh: ⵜⴰⴳⴷⵓⴷⴰ ⵜⴰⵣⵣⴰⵢⵔⵉⵜ ⵜⴰⵎⴰⴳⴷⴰⵢⵜ ⵜⴰⵖⴻⵔⴼⴰⵏⵜ, Berber Latin alphabet: Tagduda tazzayrit tamagdayt taɣerfant).

Algeria's name derives from the city of Algiers, which in turn derives from the Arabic al-Jazāʾir (الجزائر, 'the islands'), referring to four small islands off its coast, a truncated form of the older Jazāʾir Banī Mazghanna (جزائر بني مزغنة, 'islands of Bani Mazghanna').^{[page needed][page needed]} The name was given by Buluggin ibn Ziri after he established the city on the ruins of the Phoenician city of Icosium in 950. It was employed by medieval geographers such as Muhammad al-Idrisi and Yaqut al-Hamawi.

Algeria took its name from the Regency of Algeria or Regency of Algiers, when Ottoman rule was established in the central Maghreb in early 16th century. This period saw the installation of a political and administrative organisation which participated in the establishment of the Watan el djazâïr (وطن الجزائر, 'country of Algiers') and the definition of its borders with its neighbouring entities on the east and west. The Ottoman Turks who settled in Algeria referred both to themselves and the peoples as "Algerians". Acting as a central military and political authority in the regency, the Ottoman Turks shaped the modern political identity of Algeria as a state possessing all the attributes of sovereign independence, despite still being nominally subject to the Ottoman sultan. Algerian nationalist, historian and statesman Ahmed Tewfik El Madani regarded the regency as the "first Algerian state" and the "Algerian Ottoman republic".

Around ~1.8-million-year-old stone artifacts from Ain Hanech (Algeria) were considered to represent the oldest archaeological materials in North Africa. Stone artifacts and cut-marked bones that were excavated from two nearby deposits at Ain Boucherit are estimated to be ~1.9 million years old, and even older stone artifacts to be as old as ~2.4 million years. Hence, the Ain Boucherit evidence shows that ancestral hominins inhabited the Mediterranean fringe in northern Africa much earlier than previously thought. The evidence strongly argues for early dispersal of stone tool manufacture and use from East Africa, or a possible multiple-origin scenario of stone technology in both East and North Africa.