First Past the Post (FPTP)
First Past the Post (FPTP) is the system developed and used in the United Kingdom. Similar systems are used in many countries that were once British colonies, including two of the three most populous countries in the world (India, USA). This has led to members of the present British government misleadingly claiming that, "our current electoral system is one of the UK's biggest exports, used by half the voters in the world".
For a more comic take on the problems with FPTP see The Simpsons - Two party system.
Every OECD member (i.e. developed) country that uses First Past the Post has a major grassroots campaign to abolish it, including Canada, USA and of course the UK. In New Zealand a popular movement successfully replaced First Past the Post with a proportional system by referendum in 1997. Countries that use other non-proportional systems, like Australia, also have popular campaigns for PR. No country has ever changed from PR to First Past the Post. Irish politicians have twice tried to change from STV to FPTP but the voters rejected the proposal both times in referendums. For more information on the perverse effects of FPTP, see another of C.G.P. Grey's videos: Why the UK Election Results are the Worst in History.
More on Voting Systems.