Can You Explain World War 1?

Picture of the Day for 8/9/2015. A couple of years ago my great-niece Hayley messaged me on Facebook and asked me to explain World War 1 to her. Uh, that's hard to explain in a sentence or two so I encouraged her to do an internet search. I just came across this book at Barnes & Noble which would have helped. I would have bought it too if I didn't have to lug it on the plane back to Salt Lake.