Single Transferable Vote (PR-STV) is the original British proportional system.

A more plain language term for it is "proportional ranked choice voting". We use these terms (PR-STV and proportional ranked choice voting) interchangeably on this website.
 
The aim of any system of proportional representation is to produce a legislative body where the voters are represented in proportion to how they voted.

Proportional ranked choice voting is used in Ireland, two Australian territories and was used at the provincial level in Alberta and Manitoba for 30 years (the politicians got rid of it out of partisan self interest). 

It was the model recommended by the world-class BC Citizens Assembly (they called it "BC-STV").  Their top three values were proportional representation, local representation and voter choice. They also felt that BC-STV might reduce the iron grip of parties over candidates and MPs. In 2005, 58% of voters in BC chose BC-STV.

Proportional ranked choice voting is a candidate centered PR system that delivers proportional results along party lines, while giving voters the most say over which individuals within each party are elected.

Voters elect a team of local MPs in a multi-member riding using a ranked ballot.