Gibraltar is a British overseas territory located near the southernmost tip of the Iberian Peninsula overlooking the Strait of Gibraltar. The territory shares a land border with Spain to the north. Gibraltar has historically been an important base for the British Armed Forces and is the site of a Royal Navy base.

The name of the territory is derived from the original Arabic name Jabal Tariq, meaning "mountain of Tariq", or from Gibr al-Tariq, meaning "rock of Tariq". It refers to the geological formation, the Rock of Gibraltar, and the Berber Umayyad general Tariq ibn-Ziyad, who led the initial incursion into Iberia in advance of the main Moorish force in 711. Earlier, it was known as Mons Calpe, one of the Pillars of Hercules. Today, Gibraltar is known colloquially as "Gib" or "the Rock".

The sovereignty of Gibraltar is a major issue of contention in Anglo-Spanish relations. Spain requests the return of sovereignty, ceded by Spain in perpetuity in 1713. The overwhelming majority of Gibraltarians strongly oppose this, along with any proposal of shared sovereignty.

The territory covers 2.53 square miles (6.543 km²). It shares a three-quarter of a mile (1.2 km) land border with Spain and has 7½ miles (12 km) of shoreline. There are two coasts (sides) of Gibraltar – the East Side, which contains the settlements of Sandy Bay and Catalan Bay, and the West Side, where the vast majority of the population lives.

Satellite view of the Bay of Gibraltar (NASA).The climate is Mediterranean with mild winters and warm summers. There are two main prevailing winds, an easterly one known as the Levante coming from the Sahara in Africa which brings humid weather and warmer sea and the other as Poniente which is westerly and brings fresher air in and colder sea. Its terrain consists of the 1,396 foot (426 m) high Rock of Gibraltar and the narrow coastal lowland surrounding it.

Having negligible natural resources and limited natural freshwater resources, limited to natural wells in the north, until recently Gibraltar used large concrete or natural rock water catchments to collect water. This is now produced by a desalination plant using reverse osmosis, built into the Rock itself.

Gibraltar is one of the most densely populated territories in the world, with approximately 11,154 people per square mile (4,290/km²). The growing demand for space is being increasingly met by land reclamation, which comprises approximately one tenth of the territory's total area.

The Rock itself is made of limestone and is 1,396 feet (426 m) high. It contains many miles of tunnelled roads, most of which are operated by the military and hence closed to the public.

Most of its upper area is covered by a nature reserve, which is home to around 250 Barbary Macaques, commonly known as 'apes', they are the only wild monkeys found in Europe. They sometimes visit the town area. Recent genetic studies and historical documents point to their presence on the Rock before its capture by the British. A superstition analogous to that of the ravens at the Tower of London states that if the monkeys ever leave, so will the British.