Proportional representation (PR) systems allocate seats so that parties (or groups of voters) win roughly the same share of seats as their share of votes, in contrast to winner‑take‑all systems like first‑past‑the‑post.[1][2]
Most PR systems use multi‑member districts (or a whole country as one district) and then apply a formula to turn vote shares into seat shares.[3][1]
Two main families you’ll see:
As a voter, under list PR you might simply mark “Party Green” and know your vote will help determine how many Green MPs get in. Under STV, you might rank several candidates from different parties; if your first choice doesn’t need your whole vote, or is eliminated, your vote helps elect your later preferences instead of being “wasted.”[6][4][1][5]
For thinking about U.S. reform debates, that means proportional systems offer a structural way to make more votes translate into representation and to invite more parties or factions into formal politics, with reasonably strong empirical backing on turnout and representational gains, but with trade‑offs regarding complexity, coalition governance, and party system fragmentation.