House of Representatives is the name of any of many legislative bodies in many countries and sub-national states. In some countries, the House of Representatives is the lower house of a bicameral legislature, with the corresponding upper house often called a "senate". In other countries, the House of Representatives is the sole chamber of a unicameral legislature. The functioning of a house of representatives can vary greatly from country to country, and depends on whether a country has a parliamentary or a presidential system. Members of a house of representatives are typically apportioned according to population rather than geography.