Political parties allow like-minded people to combine their power with others who hold similar positions. They are essential for building coalitions. The number of viable political parties varies greatly around the world.
In democratic counties with some form of parliamentary body, political parties help build coalitions. While elected politicians are not forced to vote with their party in most countries, they generally choose to work with their party and support legislation the party proposes.
Some parties form around a particular issue. Various green parties around the world, for example, focus primarily on environmental issues. However, politicians must vote on all issues that arise, so these parties tend to take positions on a variety of issues when they gain more power. Most parties take a fundamentally conservative or progressive stance.
While most democratic nations have a wide range of parties, this does not hold true around the world. There are a number of active political parties in the United States, but various laws push the nation toward a two-party system. In other nations, the ability for parties to form may be restricted or outlawed. In order to run for office in China, anyone who is not a member of the Communist party must get permission from the government.