From Researching Virtual Initiatives in Education
A country is defined in Re.ViCa is a state which is in control of its own boundaries. The country may be a sovereign state (such as the United Kingdom) or a dependent territory, one which is "owned" by another state (such as Greenland by Denmark), provided that the owned country has considerable autonomy and/or a separate status under international treaties, for example the Åland Islands of Finland - for more details see http://en.wikipedia.org/wiki/List_of_special_entities_recognized_by_international_treaty_or_agreement.
A number of countries fulfil these criteria, but are not recognised by any other countries, or only by a few - or by many except certain important countries. Examples include Somaliland and Abkhazia. In general terms, our approach here coincides with that of Wikipedia - see http://en.wikipedia.org/wiki/List_of_states_with_limited_recognition.
For us in Re.ViCa, the state also has to have a permanent population - not just explorers or scientists or tourists. Thus for example Antarctica is not a country. The essential feature is that there are people in that country for long enough that they expect medical services and that they want to bring up their children in that country, thus requiring schools. There are always some marginal cases - see for example the entries on the countries Vatican City and British Indian Ocean Territory.
Thus each country has a population (non-zero). Wikipedia has a useful list of countries by population - http://en.wikipedia.org/wiki/List_of_countries_by_population.
In general terms, each country has a two-letter country code, but there are a few countries which do not, usually because they are unrecognised (such as Somaliland), only recently recognised (Kosovo, which several important countries do not recognise) or very small and uninhabited (for example Baker Island in the US Minor Outlying Islands). For more details on such countries see in particular http://en.wikipedia.org/wiki/List_of_states_with_limited_recognition.
In addition, the overseas departments of France (such as Réunion) do have country codes, even though they are not dependent territories - we do include these in our list of countries. This is partly for historical reasons (and perhaps political ones) but partly because the overseas departments often have unusual features (including of their educational systems) compared with Metropolitan France.
Our general approach, is like Wikipedia's, based on the Montevideo Convention
Details on this are at http://en.wikipedia.org/wiki/Montevideo_convention.
The Convention sets out the definition, rights and duties of statehood.
Article 1 sets out the four criteria for statehood:
Furthermore, the first sentence of article 3 explicitly states that "The political existence of the state is independent of recognition by the other states." This is known as the declarative theory of statehood.
A fundamental remark must be underlined: the condititions of article 1 are limited by article 11, which forbids the use of military force to obtain sovereignty.
Now see one of: