The simplest explanation of gerrymandering for non-Americans:
And yes, you do need to know this, even if you are not American. Because yes, the majority of white Americans really do want to vote for people that really, genuinely, want to start a new World War. They really do want to invade your country. Yes, including Europe. No, they are not joking.
Every state gets a number of Congress people based on population. Imagine a hypothetical square state divided into 9 districts. Most people in the state are white. Imagine that there is one majority Black city in the center of the state. The candidate that white candidates prefer, will win in 8 districts, and the candidate that Black voters prefer might win in that 1 district. 8 to 1.
A racist person might decide to redraw the district maps, so that the state is instead divided into 16 pizza slice shaped districts. In this scenario, the candidate that white Americans prefer will win 16 times, and the candidate that Black Americans prefer, will not win any districts. 16 to 0.
Racist people try to draw the racist version of the map every chance they get. Every. Chance.
The only thing stopping them from doing that, was a law called the "Voting Rights Act." White people like MLK jr. because his speeches make them feel warm and fuzzy inside. Black people like MLK, because he got the Voting Rights Act and Civil Rights Act passed.
The Voting Rights Act is now neutered by the Supreme Court. Which means Black voters can't use their congressional votes to stop racist white Americans from getting everyone killed. 🤷🏿♂️