Please explain the causes of World War I.

I am reading a book right now by John Keegan about World War
II.  He discusses a little bit about the causes of World War I because the outcome of it was part
of the cause of World War II.  Keegan says that one reason Germany attacked France was because
Germany was trying to acquire colonial empire and France, which already had a colonial empire was
in its way.

J. F. C. Fuller was a British general who wrote a book
about U.S. General Grant.  In that book, Fuller says that one reason for World War I was the
industrialization of Germany which made England feel that it would no longer be able to make so
much money off of its industry.

Concerning America's entry into WW I
on the side of England and France, I read a scholarly article when I was in college that pointed
out that American financial institutions and business men had made a lot more prewar loans to
British interests than to German interests.

Wars are always the
result of many reasons.  I have mentioned only three.