What is a multi-party system?

A multi-party system in politics is a system of government
in which more than two political parties truly have a chance to get real political
power.  This means that more than two parties have a chance to either govern on their
own or to be part of a coalition government (as the Liberal Democrats and the Tories are
part of a coalition government in England right
now).

Multi-party systems are different from one-party and
two-party systems.  A one-party system is like China's -- it is basically not a
competitive democracy because only one party has any chance at power.  A two-party
system is like that of the United States.  There can be many parties (as there are in
the US) but only two of them are relevant and can hope to gain power.  By contrast, in a
multi-party system (such as that of Germany or Israel) many parties can hope to have
some share of the power.