What was one major cause of the russian revolution in 1917?

Russia in the late 19th and early 20th century was a massive empire, stretching from Poland to the Pacific, and home in 1914 to 165 million people of many languages, religions, and cultures. Ruling such a massive state was difficult, and the long-term problems within Russia were eroding the Romanov monarchy. In 1917, this decay finally produced a revolution, which swept the old system away. Several key fault lines can be identified as long-term causes, while the short-term trigger is accepted as being World War 1.

Why do you have to ask such hard questions.