Using 'the' for a country

When it's part of a country's name e.g. The Gambia.

For kingdoms, states, etc.: the United Arab Emirates (UAE), the United Kingdom (UK), the Netherlands, the United States of America (USA) / the United States (US), the Philippines

For islands: the British Virgin Islands, the Bahamas, the Cayman Islands, the Falkland Islands, the Marshal Islands, the Solomon Islands, the Isle of Man etc.

For republics: the Dominican Republic, the Czech Republic, the Republic of China, the Republic of Congo, the Republic of Colombia, the Republic of Chile, the Republic of Chad, the Republic of Cyprus etc.