Unicameralism is what you have in the absence of a bicameral legislature. In it, all of the members deliberate and vote as a single group. There are, however, some countries which have three or more separate assemblies, chambers or houses.

By 2015, only a little less than half of the world’s national legislatures were bicameral. In this type of legislature, the members of the two chambers are often elected or selected using different methods, which vary from country to country. With this election process, the two chambers can often have a very different composition of members.

The enactment of primary legislation in a country often requires a concurrent majority which is, basically, the approval of a majority of members in each of the chambers of the legislature. When the majority of members of each chamber approve a legislation, the legislature may be called an example of perfect bicameralism.

In many Westminster system parliaments, however, the house to which the executive is responsible can overrule the other house and may be regarded as an example of imperfect bicameralism. Some legislatures lie in between these two positions, with one house only able to overrule the other under certain circumstances.

Walter Bagehot gave one of the most famous rationales for practicing bicameral legislature. In his words;

“A formidable sinister interest may always obtain the complete command of a dominant assembly by some chance and for a moment, and it is therefore of great use to have a second chamber of an opposite sort, differently composed, in which that interest in all likelihood will not rule.”

Basically, it helps to have two assemblies governing the interests of a State because the two are less likely to be swept along in any negative plans that could ultimately hurt the state than one would be.

Here are all the countries that currently practice bicameral legislature and the bodies they have;