What are the origins, immediate causes, course of phenomenon and consequences of the Nazi rule?

The origins of the Nazis, also known as National Socialism, lie in the 1920s. The ideological origins of Nazism in part can be traced to the eugenic theories of the day that posited that white northern Europeans were superior in intellect and physical qualities to people of other ethnicities and backgrounds. The belief in eugenics also went along with a sense of wounded German nationalism. This sense of nationalism arose in Germany in the 18th century with thinkers such as Johann Gottlieb Fichte and others. In part a reaction to the horrors of World War I and the sudden growth of urbanization and industrialization in Germany, German nationalism called on traditional folk culture to reinstitute vigor and pride in the country. One strain of nationalism emphasized restoring the purity of the German people through expelling elements of what made Germany a cosmopolitan, modern culture, including the Jews. Hitler adopted the anti-Semitic nature of this aspect of German nationalism.

In addition, Nazism was a reaction to Germany's defeat in the World War I, including the abdication of the Kaiser and the provision in the Treaty of Versailles of 1919 that Germany accept responsibility for the war and pay reparations. As a result of this war guilt clause, Germans felt that their pride as a nation had been wounded. In addition, Germany lost a great deal of land and had to reduce their armed forces, adding to their injured sense of nationalism. In the early 1920s, political and economic instability also led to massive inflation  in Germany. Finally, the Russian Revolution of 1917 caused a feeling of anti-communism in Germany that was also absorbed into the Nazi program.

By 1921, Hitler became head of the Nazi party. In 1923, his coup attempt in Munich led to his imprisonment, during which time he wrote the book Mein Kampf, or My Struggle, about his anti-Semitic and fascist ideas to restore a sense of pride in Germany. In 1933, the Nazis gained control of the Reichstag, or Parliament, and Hitler became Chancellor. His belief in restoring German pride led to his attacking and conquering land that Germany had lost in World War I, including the Rhineland and the Sudetenland in Czechoslovakia. Eventually, Hitler joined the Axis powers, along with Italy and Japan, and fought in World War II. His "final solution" to exterminate Jews and other "undesirable" people led to the Holocaust in which over 6 million people were exterminated in ghettoes, concentration camps, and other places. 

As a consequence of Germany's defeat in 1945 by the Allied powers, many of the ideas of Nazism were widely discredited, including eugenics. West Germany was rebuilt in the western model, and East Germany was rebuilt in a communist model. They were reunited in 1990.