What is the rule of law?

The term "rule of law" generally refers to the idea that
no person is above the law.  The idea extends to hold that even the government is not
above the law.

In systems that do not have the rule of law,
there are people and entities that can act in whatever way they want.  A government
official could, for example, simply declare that you had to do something (or not do
something) even if there was no law that said that.  A person who had enough power could
break the law and get away with it because the law would not be enforced equally in all
cases.

This is the opposite of what is expected in systems
like those of the US, Canada, and other democratic countries.  There, governments are
only allowed to act in ways that are allowed by the law.  The law applies to all
people.  We are ruled by the law and not by the whims of the people in the
government.