First past the post
Country divided into areas
Each area can have one politician
They are elected based on the votes in that area
Sounds fair but is sensitive to where boundaries are so you get weird effects ( and boundaries are always being tweaked "for fairness") ( although the tweaks always seem to be in the interest of the party making them )
It is possible for a party to get a larger share of the overall vote and not have a majority
Whats happens in practise is a party get a relatively low share of the overall vote and have complete dominance in the parliament - you can form a government with less than half the country voting for you. 2017 43% Tory, 41% labour yet labour had no say in the policies that formed.
People who like this system say it leads to strong government as one party get to rule. They despise a "hung" parliament where no one party dominates
Others say our system leads to a weak government who get their own way unchallenged, don't need to work with people or different opinions to find a better solution that works for all - it's a macho dominanat way of running things
Many seats have so many of one voter that they are "safe" seats - if you don't support that party you may as well not vote
Alternatives involve proportional representation- in it simplest form if reform get 8% of the votes they get 8% of the seats - with their candidates ranked according to how many votes they got . That means everyone's vote matters
Although the uk establishment hates the idea it does work well in other countries and scotland has a form and germany