The United States Congress and the Parliaments of Canada, the United Kingdom, Australia, and several other European and Commonwealth countries are examples of what are known as a republican system of government or a "representative democracy." Under such a system, citizens do not vote directly on legislation but instead elect representatives to a legislative body. Those representatives actually vote on legislation, in theory representing their constituencies' positions.
Both Congress and Parliament are examples of the legislative branch of government, and have as their primary task creating and amending laws. This branch is separate from the judiciary, which interprets laws and applies them to individual cases.
Both Parliament and Congress consist of upper and lower houses. In Britain the upper house (the House of Lords) contains peers (members of the nobility), appointed members, and certain Bishops and Archbishops of the Church of England, while members of the Canadian Senate are appointed and those of the United States Senate elected. Members of both Congress and Parliament represent geographical areas, known as electoral districts, ridings (Britain and Canada), or constituencies.