Islay is the southernmost island of the Inner Hebrides of Scotland. Known as "The Queen of the Hebrides", it lies in Argyll and Bute just south west of Jura and around 40 kilometres (22 nautical miles) north of the Northern Irish coast. The island's capital is Bowmore where the distinctive round Kilarrow Parish Church and a distillery are located. Port Ellen is the main port.

Islay is the fifth-largest Scottish island and the eighth-largest island of the British Isles, with a total area of almost 620 square kilometres (240 sq mi). There is ample evidence of the prehistoric settlement of Islay and the first written reference may have come in the first century AD. The island had become part of the Gaelic Kingdom of Dál Riata during the Early Middle Ages before being absorbed into the Norse Kingdom of the Isles.

The later medieval period marked a "cultural high point" with the transfer of the Hebrides to the Kingdom of Scotland and the emergence of the Clan Donald Lordship of the Isles, originally centred at Finlaggan. During the 17th century the power of Clan Donald waned, but improvements to agriculture and transport led to a rising population, which peaked in the mid-19th century. This was followed by substantial forced displacements and declining resident numbers.

Today, Islay has over 3,000 inhabitants, and the main commercial activities are agriculture, malt whisky distillation and tourism. The island has a long history of religious observance, and Scottish Gaelic is spoken by about a quarter of the population. Its landscapes have been celebrated through various art forms, and there is a growing interest in renewable energy in the form of wave power. Islay is home to many bird species such as the wintering populations of Greenland white-fronted and barnacle goose, and is a popular destination throughout the year for birdwatchers. The climate is mild and ameliorated by the Gulf Stream.

Islay was probably recorded by Ptolemy as Epidion, the use of the "p" suggesting a Brittonic or Pictish tribal name. In the 7th century Adomnán referred to the island as Ilea, and the name occurs in early Irish records as Ile and as Íl in Old Norse. The root is not Gaelic and is of unknown origin.

In 17th-century maps, the spelling appears as "Yla" or "Ila", a form still used in the name of the whisky Caol Ila. In poetic language, Islay is known as Banrìgh Innse Gall, or Banrìgh nan Eilean usually translated as "Queen of the Hebrides" and Eilean uaine Ìle – the "green isle of Islay" A native of Islay is called an Ìleach, pronounced [ˈiːləx].

The obliteration of pre-Norse names is almost total, and placenames on the island are a mixture of Norse and later Gaelic and English influences.

Port Askaig is from the Norse ask-vík, meaning "ash tree bay" and the common suffix -bus is from the Norse bólstaðr, meaning "farm".