Proportional representation

[Little_Girl]

Just a side note: If you arent familiar with the various electoral (voting) systems around the world, please do not read this as the wording may confuse you.
An electoral (i.e., voting) process in which full representation of all parties who have received votes is achieved by closely matching the percentage of party votes to the percentage of seats allocated in [legislative] assemblies.
There are 3 known ways of achieving proportional representation ([PR]) in electoral systems.

Party-List PR: Theres a list of pre-determined candidates (closed-list) or candidates that the voters can rank (open-list), along with some mathematical formula of allocating the seats (DHondt or Sainte-Lague). Countries which use Party-List PR include Israel (where the country is one closed-list [constituency]) and the Netherlands (open-list).
Additional-Member System ([AMS]), Mixed-Member System ([MMS]): Two votes, one vote for a [legislator] (MP -- Member of Parliament -- in places like the UK and New Zealand) to represent a single-member constituency (under [plurality] voting), the other vote for a party (under party-list PR). In places like Germany, a certain number of seats are blockaded off for party-based legislators. Besides Germany, New Zealand uses this (along with calculating party-list seats via the Sainte-Lague method) for its House of Representatives.
Single [Transferable] Vote ([STV]) (in a multi-member constituency): Usually 3 to 6 candidates per constituency. Voters number their [ballot] according to their preferences. The first preferences are calculated first and candidates must achieve a [quota] (determined by the number of votes and the number of vacant seats) in order to be elected; if none of them meet the quota, the lowest-voted candidate gets eliminated and his/her 2nd preferences allocated to the next candidate, etc., until all the constituency seats are filled. Australia uses this to elect its Senate (upper house).

The 1998 [Jenkins] Commission in the UK also suggested a broadly-PR type of voting system called Alternative Vote Top-Up, a variant of Additional-Member/Mixed-Member where voters number their ballot according to preferences to determine an electorate MP in single-member constituencies (just like Australias [preferential] voting for its House of Representatives). The other vote is a party vote, candidates [on that list] for each county.
A few notes on proportional representation:

Parties are less likely to gain majorities in legislative assemblies, very likely resulting in coalition governments.
Third parties, which are often disadvantaged under [FPTP] (first-past-the-post), often want PR so they can get more seats but not necessarily a majority. Examples being the [UKs] [Liberal Democrats] and Canadas [NDP].

For more on PR, just type proportional representation voting in your favorite search engine.

[Dianne]

a political system in which parties are represented in parliament according to the number of people who voted for them