There are many resources that you can use online to learn about the Holocaust. A Wikipedia page is even available that provides an overview of the event as well as the details of exactly what happened during the years while Hitler ruled Nazi Germany. The Holocaust is one of the biggest cases of genocide in modern history and has caused a lot of controversy. Information on the event is fairly easy to find, however, because of all of the interest in the events that transpired and led to the murder of more than 11 million people over the course of 12 years.
During the Holocaust, Jews were stripped of their rights as citizens and eventually herded into ghettos, concentration camps, and then gas chambers where they were killed. At first, Hitler implemented discrimination laws that boycotted Jewish businesses and set the stage for future discrimination. These were known as the Nuremburg Laws. Then, laws removed rights and essentially put Jewish people in a place where they were treated as less than human.
Jews and others who had been deemed inferior were forced out of their homes and into ghettos, where they lived in squalor. Then, once camps were built, they were sent to various camps for labor, torture, medical experimentation, and eventually, death. This event killed approximately 2/3 of the Jewish population in Europe, as well as about 1.5 million children. The Holocaust Wiki page provides facts about which people were targeted, how many of them were targeted, and how the entire event transpired. It begins with the rise of Hitler to power and provides facts and insight through the end of World War II and the liberation of Germany and the camps throughout Europe.
The scale of the Holocaust started out very small, but quickly escalated due to the large following of the Nazi party and the inability of other countries to fight off their advances. Nazis believed that Germany had been misled by its leaders in World War I and they wanted to build a master race to advance the success of the country as a world power. They believed in white supremacy, and were quick to discriminate against and target anyone that didn't fit their goals based on race, gender, sex, ethnicity, religion, and other factors. The in-depth explanation of the Holocaust on Wikipedia offers detailed accounts of every aspect of the Holocaust from the Nuremburg Laws to the concentration camps and everything in between.