Was there really a real reason or cause for World War 1?

I know that Franz Ferdinand the heir to the throne of Austria-Hungary was inated and Austria-Hungary got all pissed at Serbia and declared war on them then the rest of the world joined on different sides because of treaties and being allies of that certain country that joined but really was there really a cause to fight. What were those soldiers on the Western Front really fighting and dieing for? That's something I always wanted to know. Also I want to know what was the effect of World War 1 and what did the Allies gain and what did the Central Powers lose?