Addresses are hierarchical labeling systems that categorize locations starting with the smallest definable geographic area, such as an apartment, and expanding out to the larger geographic areas with country being the largest. For most of the world this is relatively straightforward, but in my motherland, it's anything but. In fact, it's about as complicated as it gets.
The geopolitical landscape of the British Isles is a complex tapestry, woven from centuries of history, conflict, political evolution, and cultural diversity. In fact, most people in the British Isles neither know nor care about this complex structure. We like the fact that it's complicated! And we use that complexity to justify how a group of small islands, off the coast of northern Europe can still feel important and relevant in today's world.
The United Kingdom of Great Britain and Northern Ireland
Let's start with what is officially known as the United Kingdom of Great Britain and Northern Ireland, often abbreviated as the UK, is a sovereign country represented by the Union Jack flag, comprising four (this is where it gets complicated) constituent countries: England, Scotland, Wales, and Northern Ireland.
Three of these countries (England, Scotland, and Wales) are on the same island, Great Britain, the largest in the British Isles. Before the 1707 Acts of Union, which united the Kingdom of England and the Kingdom of Scotland and introduced the "great" intensifier, it was just Britain. Before that, it was Albion (for King Arthur scholars) and the Brythonic Isles (to the Celts of Wales and Cornwall).
Northern Ireland, located on the island of Ireland to the west, shares a border with the Republic of Ireland to the south and west. The complex history of Northern Ireland includes centuries of political and sectarian strife – and not something to talk about here. One thing that has always struck me as interesting from an addressing perspective is that the Royal Mail delivers to Northern Ireland, but the Ordnance Survey is the National Mapping agency for Great Britain only and does not cover Northern Ireland.
The British Isles
As we zoom out geographically, the British Isles is a legal term used to refer to the islands under British sovereignty, including the islands of Great Britain, the Isle of Man in the Irish Sea, and the Channel Islands in the English Channel close to the northern coast of France, of which there are five. These islands are British Crown Dependencies and not part of the United Kingdom. They are self-governing with their own legislative assemblies. Many people have heard of the two big islands of Jersey and Guernsey, famous for their offshore banking businesses. Interestingly Alderney, Sark and Herm, while independent in many respects including the addressing perspective, they are within the Bailiwick of Guernsey (i.e. within the legislative jurisdiction of Guernsey).
The British Isles is an important concept politically because the Head of State for all of these is the current British Monarch, King Charles III. He is also the Head of State for countries like Canada and Australia and a bunch of Caribbean islands.
Geographical vs. Political Use of "British Isles"
Zoom out even further and use the term "British Isles" to describe all the islands of Great Britain, the Island of Ireland, and over 6,000 smaller islands. It's important to know that you should be cautious when using this term because it refers only to a geographical grouping of islands and does not imply any political union. The Republic of Ireland is a sovereign nation, independent from the United Kingdom, and the use of "British Isles" is sensitive due to complex historical and political reasons.
So, if you followed all of that…
Using the nice picture I created for you, you can infer that when using addresses for "Britain" you will need to use the name of each country or island as part of the address. And for official government activities. But it's worth noting the Royal Mail, which delivers to all of the British Islands (the "Royal" word gives away its jurisdiction) doesn't insist on it because it gets all the information it needs from the Post Code.