The UK uses 'First Past the Post' (FPTP) for general elections. In this system, each constituency elects one MP, and the candidate with the most votes wins, even if they receive less than 50% of the total votes. For example, in a constituency with 100,000 people, only one MP is elected, regardless of how the remaining votes are distributed.
In contrast, 'Proportional Representation' (PR) allocates seats based on the percentage of votes each party receives. Larger, multi-member constituencies are used. For example, in a region with 100,000 voters and 10 seats, a party winning 40% of the votes would get 4 seats.