We know it's probably pretty hard for you to imagine being angry and hate-filled to the point of violating the basic rights of millions of innocent people.
But Adolf Hitler had no such problem imagining that—and he had no problem doing lots of horrible things to make it happen.
When he came to power in 1933, ol' Hitler was super peeved at what the end of World War I had done to Germany—the country had been forced to take complete responsibility and pay lots of hefty war reparations. The country was depressed, both economically and emotionally, and things only got worse when the U.S. stock market crashed and plummeted the whole world into the Great Depression.
And what's a sociopathic mustachioed man to do when things aren't going his way? If you had asked Hitler, he would've advised blaming all the people he hated—starting with the Jews.
He began infringing on the rights of Jewish populations within two years of coming to power. The Nuremberg Race Laws were designed to slowly exclude Jews from the rest of society so it would be easier to execute the final part of his plan.
The Final Solution was the Nazi plan to completely eradicate the Jewish race, first from Germany and other occupied territories before eventually moving on to the whole world.
We know this grand plan for world domination sounds like a cliché, but it quickly became a terrifying reality when the Nazis built huge concentration camps—i.e., centers of murder—throughout occupied Europe. Those who weren't sent immediately to the gas chambers were forced to live in less-than-human conditions and often were killed through a combination of starvation, disease, and physical brutality.
Before World War II ended in 1945, the Nazis—under Hitler's leadership—had murdered 11 million people, 6 million of whom were Jews. It remains the largest human rights violation in human history, and Hitler's actions were directly responsible for the creation of the Commission on Human Rights and the Universal Declaration of Human Rights.
The rest of the world wanted an international agreement that would prevent another dictator from doing such horrible things ever again.