Mein Kampf (My Struggle) was a book written by Adolf Hitler and Rudolf Hess. Rudolf Hess helped Hitler write the book, but he is not mentioned as an author. The book consists of two parts. The first part was written by Hitler while he was in jail in Landsberg am Lech. He was put in jail after a failed putsch, in 1923. He wrote the second part after his (early) release from jail. From 1926 to 1930, both volumes were sold separately, at the price of 12 Reichsmark each. In 1930, both volumes were published as one book. 

There were several editions between 1925 and 1945. With each new edition, the text was revised as well. This was done to clarify those parts of the text that were unclear. Probably, ghostwriters around Hitler did this work.

In the book, Hitler describes (talks about) his view of greater Germany. He also describes his future plan for Jews. When he came to power, in 1933, he realized (made happen) some of those plans. This resulted in a genocide known as The Holocaust. The book was given away for free at civil registry offices during the time when the Nazi government had power in Germany. The reason for giving the book away for free was because in part, the book was propaganda, and giving it away free was a way to recruit members.

After the Second World War, the book was made illegal to reprint or sell new copies in Germany and Austria. It is not illegal to own a book, and it is also not illegal to sell or buy such books second-hand.

The book has been called the "most evil book in history". Historians and journalists who have read also say that it is a badly written book.

The contents in short 
 Hitler wanted to unite Austria with Germany. (The annexation, or "Anschluß," took place in 1938. The sympathetic Austrian government asked Hitler to annex Austria to be part of the "Großdeutsche Reich" (The Greater German Reich).
 Several antisemitic beliefs in the book are developed. Special care is taken to portray Marxism as something very bad which had been a Jewish creation.
 The concept of nationally oriented socialism (Nationalsozialismus, that's where the Allied word Nazi (National Sozialistishe) comes from as they did not call themselves Nazi's). A war should be a war of races, not one of the different classes of society against each other. From this conflict, sympathy from German class could be amassed.
 The political system of the Soviet Union referred to as Bolshevism should be split into parts. This should be done through what is called a war of the races (Rassenkrieg in German).
 According to the book there is not enough space for the German People to live. Winning such a race war would give the people (of "Aryan" blood) more space to live (Lebensraum), in the east. (At the time the book was written Germany was roughly the size of Texas).
 Germany should not fight a war on two fronts. Resultingly, England would be a good strategic partner in a war to come. 
 Parliamentary or Democratic governments should be replaced with a state where a single leader makes decisions. This was believed to be more in the interest of the people.
 The structure of the NSDAP, as outlined in the second volume is developed.
 Some autobiographic stories, and a history of the NSDAP, both till 1924.

Nazism
1925 books