Nazi Germany refers to the government of Germany that lasted from 1933 until 1945. It was led by Adolf Hitler and the Nazi party - the NSDAP - and it was based on the ideology of National Socialism, a variant of fascism and totalitarianism.
The Nazi regime was characterized political control of every aspect of society (Gleichschaltung), and by brutal persecution, especially against targeted minority groups such as Jews, Gypsies, and homosexuals, as well as political opponents. This persecution reached a peak in the last years of the regime, in which some 6 million Jews, 10 million Slavs, and sundry others, were systematically killed. This genocide is refered to as the Holocaust.
In 1939 Germany's actions lead to the outbreak of World War II in Europe -- Poland, France, and the Netherlands were invaded, and Germany declared war on the United Kingdom. After invading Greece and North Africa, Germany invaded the Soviet Union in 1941. It declared war on the United States in December of 1941. After losing the Battle of Stalingrad in 1943 and the Battle of Normandy in 1944, the regime started to disintegrate quickly, losing ground to the Alied forces in the west and south and the Red Army and the Polish Army in the east. By spring of 1945 German territory was invaded. In April, 1945, Hitler committed suicide and Germany finally surrendered in the first week of May.
After the war, Nazi leaders were put on trial by the Allied tribunal at Nuremberg for crimes against humanity.