The Liberal government announced on Wednesday the formation of an all-party committee to study alternatives to the way we elect members of Parliament, promising an "open and transparent engagement process that is inclusive to all Canadians."

Here's a guide to our current electoral system and some of the possible alternatives.

First past the post, or single-member plurality: The person with the most votes in a riding wins the seat. The candidate doesn't need a majority (50 per cent plus one vote), but rather a plurality of votes cast — more than any of the other candidates. The party that collects the most seats in this way gets to govern.

Benefits: Simple and familiar, it's been used in Canada for 150 years.

Drawbacks: First past the post routinely results in MPs elected to represent a riding even though more than half of their constituents didn't vote for them. Since Confederation, there have been only six governments take office with more than 50 per cent of the popular vote, as Maryam Monsef, minister of democratic institutions, noted in a statement Wednesday.

Today we deliver on the campaign promise to introduce a motion to establish an all-party committee to study <a href="https://twitter.com/hashtag/electoralReform?src=hash">#electoralReform</a>. <a href="https://twitter.com/hashtag/CdnDemocracy?src=hash">#CdnDemocracy</a> —@MaryamMonsef

Preferential, or ranked, ballot: Voters rank the candidates — first choice, second choice and so on. If no candidate emerges with a majority after the first count, the lowest-ranked candidate comes off the ballot, and their votes are redistributed according to the second choices cast. This continues until one candidate achieves a majority of 50 per cent plus one vote.

Benefits: Proponents say it would eliminate vote splitting and strategic voting, and reduce negative campaigning. Ontario has said it will offer municipalities the option to use this system starting in 2018 — something Dave Meslin, founder of the Ranked Ballot Initiative of Toronto, has been advocating for years.

Drawbacks: Fair Vote Canada says a ranked ballot would be useless in a system like ours, where only one member is elected per riding. "It would continue to waste about half of votes cast, produce distorted overall results (false majorities) and replicate many of the problems experienced under our current system," the group says on its website. A ranked ballot is more effective when it's built into a proportional system, Fair Vote Canada says.

Proportional representation: The percentage of seats a party holds corresponds to the percentage of votes it receives. It's a simple idea employed by many Western democracies, but with many variations.

Benefits: Proponents say proportional representation more accurately reflects the will of the people.

Drawbacks: The main criticism is that it leads to coalition governments, which can be fragmented and ineffectual because they cannot find enough common ground, according to the ACE Electoral Knowledge Network, a collaborative elections information project of which Elections Canada is a partner. Tiny parties — or even extremist parties — can hold larger parties ransom in legislative negotiations.

Rather than this charade, the Libs should have just put their preferred system out and get reaction to it. —@MichelleRempel

Mixed-member proportional representation (MMP): Voters have to make two choices on the ballot: one for a candidate to represent them and one for a party. Roughly half to two-thirds of seats would be filled by the individual candidates who win their ridings, as in our current first-past-the-post system; the remaining seats would be allotted according to each party's share of the popular vote, with the candidates taken from a predetermined list.

Benefits: "The overall results in these systems are highly proportional, that is, for each party, the percentage of seats it obtains in the legislature closely mirrors its share of the vote," says the Law Commission of Canada, which recommended Canada switch to mixed-member proportional representation in its 2004 report to then justice minister Irwin Cotler.

Drawbacks: "MMP can create two classes of legislators — one group primarily responsible and beholden to a constituency, and another from the national party list without geographical ties and beholden to the party," says the ACE Electoral Knowledge Network. "This may have implications for the cohesiveness of groups of elected party representatives."

Woo hoo! Liberals have (finally) announced <a href="https://twitter.com/hashtag/electoralreform?src=hash">#electoralreform</a> process! Details to come but let the work begin & listen to Cdns <a href="https://twitter.com/hashtag/cdnpoli?src=hash">#cdnpoli</a> —@nathancullen

Single-transferable vote system: The number of electoral districts is greatly reduced, with each represented by two to seven members. Voters rank some or all of the candidates in order of preference. In the first count, any candidate who has enough first-preference votes is elected automatically. In subsequent counts, the elected candidate's surplus votes are transferred to the next choices in fractional amounts. After each successive count, candidates who reach the quota are elected, and those who don't are eliminated.

Benefits: The B.C. Citizens' Assembly, which proposed moving to a single-transferable vote for provincial elections, says the system is easy and fair and empowers voters.

Drawbacks: B.C. voters twice came just short of passing a proposed move to the single-transferable vote, in 2005 and 2009. The No STV campaign said the newly drawn electoral districts would be too large, with populations between 200,000 and 300,000, and that the system made it possible for a district to elect all of its candidates from one part of the community and leave others unrepresented.

Prime Minister Justin Trudeau promised 2015 was the last election to be fought on first-past-the-post. What shape could electoral reform take? 2:39

P3 (proportional-preferential-personalized): Each riding elects between three and five MPs (determined by population density). Voters rank parties in order of preference, then pick their preferred candidate from their top-choice party. The seats in each riding are distributed according to the party rankings. If any party fails to get enough votes to win a seat, they are dropped off and their votes redistributed according to voters' second choices. Then, the candidates are installed into the number of seats the party won: the top two Conservative candidates take the two Conservative seats in the riding, for instance.

Benefits: Stéphane Dion, former leader of the Liberal Party and current foreign affairs minister, has repeatedly made the case for P3, saying it would correct the "harmful regional distortion" we have seen in the past, increase voter turnout and bring about a more "representative" Parliament.

"Today, voters are helpless when they are stuck for four years with a lazy, incompetent or absentee MP," he says in an article on his website, though he stresses the views are his own and do not represent those of the party. "In the new system, constituents would be able to deal with another elected official. Competition among the five MPs in a single riding would provide Canadians with better territorial representation."

Drawbacks: As a form of proportional representation, P3 would have the same potential drawbacks as other PR systems.

Special comm on electoral reform - both Bloc and Greens will be on committee, but with no right to vote. We really need ppl to engage! <a href="https://twitter.com/hashtag/GPC?src=hash">#GPC</a> —@ElizabethMay

Mandatory, or compulsory, voting: Citizens who fail to show up on election day may be subject to a fine. As the Library of Parliament's electoral primer points out, citizens are not required to vote, just to register and present themselves at polling stations. They can abstain from voting or spoil their ballots if they wish.

Benefits: Increases voter turnout and engagement.

Drawbacks: Might be considered undemocratic to force citizens to participate, and doesn't necessarily mean the electorate makes more informed choices. Also, enforcing penalties can be costly.