An upper house is one of two chambers of a bicameral legislature, the other chamber being the lower house. The house formally designated as the upper house is usually smaller and often has more restricted power than the lower house. A legislature composed of only one house is described as unicameral.

Bicameralism is a type of legislature that is 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 2022, roughly 40% of the world's national legislatures are bicameral, while unicameralism represents 60% nationally and much more at the subnational level.