Party system: network of interrelationships between and among parties. Crucial to structuring the function of political system practice. Presence of parties does not actually confirm a party system. Concern not simply number of parties, but the nature of their relationship. Strictly speaking, a contradiction in terms -> power monopoly. When we have a single party system, what that means is there is one party in power and there are no regular elections or maybe none, the government is the party. E. g, china"s one party system, get there by merit and not by election. Dominated by two parties, doesn"t have to be limited to two parties necessarily. Similar to one-party systems -> regular, competitive elections dominated by one- party. In dominant systems, there are regular competitive elections, just so happens they are dominated by one party (not rigged) (meant to make us feel we have real choices) Usually seen as a regrettable and unhealthy phenomenon.