Describe the various party systems existing …

Party systems:
One-party system:

• In some countries, only one party is allowed to control and run the government. It is called one-party system.
• We cannot consider one-party system as a good option because this is not a democratic option.
• Any democratic system must allow at least two parties to compete in elections and provide a fair chance for the competing parties to come to power.
  Example: Communist Party of China.

Two-party system:

• In some countries, power usually changes between two main parties.
• Here, only the two main parties have a serious chance of winning majority seats to form the government.
  Example: USA and UK.

Multi-party system:

• If several parties compete for power and more than two parties have a reasonable chance of coming to power, either on their own or in alliance with others, it is called a multi-party system.
• The multi-party system often appears very messy and leads to political instability.
• At the same time, this system allows a variety of interests and opinions to enjoy political representation.
  Example: India.

Major Coalitions—NDA, UPA, Left Front.