Comparative political science terms the system of government by political parties in a democratic country as a party system. Politicians are viewed as having common characteristics: they control the government, have mass popular support, and have internal mechanisms to control funding, information, and nominations.
Researchers studying the United States, especially James Bryce and Moisey Ostrogorsky, developed the concept, which has been applied to other democracies. Party systems are classified by Giovanni Sartori, who devised the method that is most widely used today. The number of relevant parties and fragmentation of party systems should be used to categorize party systems, he suggested. Depending on how many parties there are, party systems can be distinguished.