There are many party system. There is a one-party system where only one party is allowed to run the government, like China.
Then, there is two, parties system where only two parties contest election like the USA.
Multi-party system: here several parties contest the election. Eg. India
The one-party system is not good for the country:
a. In a one-party system, people do not have the option to elect a different leader. They had to choose the same leader whether he is liked by the citizens or not.
b. There is a lack of competition which may result in non-fulfilment of promises by the single party.
