Proportional representation (PR) characterizes electoral systems in which divisions in an electorate are reflected proportionately in the elected body. The concept applies mainly to geographical, and to ideological partitioning of the electorate. For instance at the European parliament each member state has a number of seats that is (roughly) proportional to its population (an instance of geographical representation). The same logic prevails when voters vote for parties (ideological partition of the electorate). If "n"% of the electorate support a particular political party or set of candidates as their favorite, then roughly "n"% of seats will be won by that party or those candidates. The essence of such systems is that all votes contribute to the result—not just a plurality, or a bare majority. The most prevalent forms of proportional representation all require the use of multiple-member voting districts (also called super-districts), as it is not possible to fill a single seat in a proportional manner. In fact, PR systems that achieve the highest levels of proportionality tend to include districts with large numbers of seats.