Northern Ireland is a part of the United Kingdom that is variously described as a country, province, territory or region. Located in the northeast of the island of Ireland, Northern Ireland shares a border to the south and west with the Republic of Ireland. In 2011, its population was 1,810,863, constituting about 30% of the island's population and about 3% of the UK's population. The Northern Ireland Assembly, established by the Northern Ireland Act 1998, holds responsibility for a range of devolved policy matters, while other areas are reserved for the British government. Northern Ireland co-operates with the Republic of Ireland in several areas.