The partition of Ireland was a result of the Government of Ireland Act 1920, which established two separate parliaments, one for Northern Ireland and one for the rest of Ireland in response to rising tensions between Catholics and Protestants in Ireland, and the desire of Protestant communities in the northeast of the country to remain part of the United Kingdom.
The partition was accompanied by violence and conflict and created a legacy of political and social divisions that continue to influence politics in Ireland today. Northern Ireland remained part of the United Kingdom, while the rest of Ireland became the Irish Free State, which later became the Republic of Ireland.
The Good Friday Agreement, signed in 1998, provided for the possibility of a referendum on Irish reunification if it appeared likely that a majority of the people of Northern Ireland would vote in favour of it. In recent years, there has been increasing discussion and speculation about the possibility of a reunification referendum, particularly in light of the United Kingdom's decision to leave the European Union. Some people argue that a united Ireland would allow Northern Ireland to remain in the EU because the Republic of Ireland is currently a member of the EU, and it would be expected that any new country formed through reunification would inherit the same status.
If Northern Ireland were to remain part of the United Kingdom, it would no longer be part of the EU following Brexit. This would mean that the border between Northern Ireland and the Republic of Ireland would become an external border of the EU.
There are some who argue that a united Ireland could benefit from EU membership, as it would have access to the single market, the EU's common trade policy, and other benefits. However, there are also concerns about the potential economic and political implications of reunification, particularly for the people and communities of Northern Ireland.
In general, the Irish government and many Irish political parties, particularly those with a nationalist or republican outlook, support the principle of reunification and believe that it would be a positive development for the island of Ireland. They argue that a united Ireland would bring an end to the political and social divisions caused by partition, and would provide a better future for all of the people of the island. Recent polls also suggest that there is a growing interest in the possibility of reunification among the Irish population in the Republic of Ireland