Bicameral means that there are two houses. This means that if a certain piece of legislature needs to be passed, both houses have to agree on it. It was developed during the aristocratic ages when one house comprised aristocrats while other worked for the people. The advantage is the democratic process that is involved to a much higher degree than just by having one house of rich politicians who decide. In the Great Compromise, it was decided that every state, no matter its size, will have representatives in the Congress who are capable of voting.
