Great Britain is an island lying off the western coast of Europe, comprising the main territory of the United Kingdom.
Great Britain is also used as a political term describing the combination of England, Scotland, and Wales, the major political entities that together include all the island's territory.
The term Britain is sometimes used to mean Great Britain, and both are often used to refer to the United Kingdom, which also includes Northern Ireland. Great Britain was often used in the past as a convenient abbreviation for the unwieldy "United Kingdom of Great Britain and Northern Ireland". While it may be seen as inaccurate, the abbreviation Great Britain is still often used by official bodies as a synonym for the UK in some contexts (for example, the UK competes in the Olympic Games as Great Britain and the UK uses the International license plate code of 'GB'). This is discussed further under Britain.
Great Britain stretches over approximately ten degrees of latitude on its longer, north-south axis. Geographically, the island is marked by low, rolling countryside in the east and south, while hills and mountains predominate in the western and northern regions. Before the end of the last ice age, Great Britain was a peninsula of Europe; the rising sea levels caused by glacial melting at the end of the ice age caused the formation of the English Channel, the body of water whch now divides Great Britain from the European mainland.
The climate of Great Britain is milder than that of other regions of the Northern Hemisphere at the same latitude, because the warm waters of the Gulf Stream pass by the British Isles and exert a moderating influence on the weather. Cool, but not cold, temperatures, clouds more often than sun, and abundant rain are the rule in most years.
The term Great Britain was first widely used during the reign of King James VI of Scotland, I of England to describe the island, on which co-existed two separate kingdomss ruled over by the same monarch. Though England and Scotland each remained legally in existence as a separate state with its own parliament, collectively they were sometimes referred to as Great Britain. In 1707, an Act of Union joined both states. That Act used two different terms to describe the new all island state, a 'united Kingdom' and the 'Kingdom of Great Britain'. The former is generally though not universally regarded as a description of the union rather than its name. Most reference books describe the all-island kingdom that existed between 1707 and 1800 as the Kingdom of Great Britain.
In 1801, under a new Act of Union, this kingdom merged with the Kingdom of Ireland, over which the monarch of Great Britain had ruled. The new kingdom was unambiguously called the United Kingdom of Great Britain and Ireland. In 1922, twenty-six of Ireland's thirty-two counties left to form a separate Irish Free State. The remaining truncated kingdom is now known as the United Kingdom of Great Britain and Northern Ireland, which also now includes a number of Overseas Territories. Though sometimes the term 'Great Britain' is used when referring to the United Kingdom, with the United Kingdom minus Northern Ireland being referred to as 'the mainland', this is factually incorrect; it is simply 'Great Britain'.
Often the terms Britain and British refer to the whole of the UK or its predecessors, or institutions associated with them, and not just Great Britain. For example, United Kingdom monarchs are often called "British monarchs"; United Kingdom Prime Ministers are often called "British Prime Ministers". Such usage is generally seen as correct. However the use of the term English for British, as in "Queen of England" is clearly incorrect; England in a sense of a separate state has not existed since 1707.
The term Islands of the North Atlantic or IONA has also been used more recently for the British Isles. It was created as a neutral term for use in efforts to achieve agreement on a more widely acceptable political structure for Northern Ireland. However, it remains unknown to most of the British population, and seems likely to achieve little recognition outside of the narrow political circles in which it was coined.