Bicameralism is a type of legislature, one divided into two separate assemblies, chambers, or houses, known as a bicameral legislature. Bicameralism is distinguished from unicameralism, in which all members deliberate and vote as a single group. As of 2015, about 40% of world's national legislatures are bicameral, and about 60% are unicameral. Often, the members of the two chambers are elected or selected by different methods, which vary from jurisdiction to jurisdiction. This can often lead to the two chambers having very different compositions of members.