Name of the electoral system used to elect Members to the main house (House of Commons) in the Westminster UK Parliament. Otherwise know as Simple Plurality.

A nation using this system divides itself into geographical areas called constituencies that have roughly the same number of citizens (constituents) living in each. Come election time, a set of candidates stand in each constituency, either for a political party or independently. The voter is faced with a list of these candidates and chooses one.
The candidate who wins the constituency is simply the one who has most votes.
The winner of each constituency is made a Member of Parliament. The leader of the party with the most Members of Parliament is made the Prime Minister - the head of the Government.

Advantages of the system are that it produces strong government, is simple to execute and understand and that it maintains a strong constituency/MP link. Disadvantages are that it is entirely disproportionate and that people feel that their votes are wasted (hence they don't vote).

FPTP is a very old system, based on ideas of democracy that no longer really apply. This is why it is only used here in the UK, a very old 'democracy' and why there is quite a strong electoral reform movement.