I.Introduction 1.Why pollical parties?Modern democracy would be meaningless without political parties.The party is the only institution that has the purpose of developing broad policy and leadership choices and then presenting them to the voting public for acceptance or rejection. 2.Party systems in the world 3.How electoral system affects the number of political parties? 1)single-member/simple majority electoral system 2)pure proportional representation system 3)multi-member electoral system 4)a combination of single-member/simple majority and proportional representation electoral systemI. Introduction 1. Why pollical parties? Modern democracy would be meaningless without political parties. The party is the only institution that has the purpose of developing broad policy and leadership choices and then presenting them to the voting public for acceptance or rejection. 2. Party systems in the world 3. How electoral system affects the number of political parties? 1) single-member/simple majority electoral system 2) pure proportional representation system 3) multi-member electoral system 4) a combination of single-member/simple majority and proportional representation electoral system