The history of Britain and Ireland is long, complicated and horribly messy, and as a result, lots of people get the words that describe the region mixed up.
As well as being inaccurate, misusing these words can cause a lot of offence, so it’s important to use them right. Here is a brief description of how these words are used, and how you can use them without upsetting anyone.
The UK
The UK, or “United Kingdom of Great Britain and Northern Ireland”, is the Sovereign state composed of the constituent countries of England, Wales, Scotland, and Northern Ireland. The adjective for the UK is “British”.
Important note: It’s worth remembering that not everyone within the UK identifies as British. In Scotland, many people see themselves as only Scottish, while in Northern Ireland, many people identify entirely as Irish, not British. Both regions have major separatist movements, so this is a sensitive topic for a lot of people. This is also true, albeit to a lesser extent, in Wales, where a many people identify as Welsh but not British, and even the English county of Cornwall, where there is a growing movement towards Cornish nationalism.
As always, it’s best to respect people’s identities, so be careful who you call “British”, in case they strongly identify as something else. And perhaps even more importantly, don’t call non-English people English!
Great Britain
Great Britain is the big island. As a geographic term, it includes all of mainland England, Scotland, and Wales. Politically, this is expanded out to include all the smaller islands of those countries too.
Britain
Britain is a more ambiguous term:
Politically it is often used as a short, informal name for the United Kingdom. Which, since the UK is “British”, makes sense. It has been used this way by politicians and scholars for a long time.
However, it is also sometimes used as short for “Great Britain”, which can get very confusing. This means either of the maps above could represent Britain. For this reason, this word is avoided in most official settings, in favour of “United Kingdom” (for the country) or “Great Britain” (for the island).
Ireland
The Republic of Ireland is not part of the UK, but worth including here because it is very entangled in this mess of names and identities.
Ireland, like “Britain”, has 2 different meanings depending on context.
Ireland geographically is an island, that includes the Republic of Ireland and Northern Ireland.
Ireland politically a sovereign nation entirely independent of the UK. To differentiate it from the island of Ireland, it is can be called the Republic of Ireland. Northern Ireland is not part of the Republic of Ireland.
“Irish” refers to anybody from the island who identifies as Irish, including those in Northern Ireland.
Northern Irish people have the option to claim Irish citizenship, get Irish passports, and play for Irish national sports teams.