The United Kingdom had the name Great Britain between the Acts of Union 1707 and the Act of Union 1800. Northern Ireland is not on the island of Great Britain, but it is part of the United Kingdom of Great Britain and Northern Ireland. (The island of Ireland contains nearly all of the Republic of Ireland, which is a sovereign state, as well as nearly all of Northern Ireland.) Great Britain is not the official name of a present-day state. Some people call the United Kingdom "Great Britain" and people from other parts of the United Kingdom may not like it when people make this mistake.