It's gonna be a bad day

It is actually quite easy for a world war to begin because many countries are allied with other countries and in the event of war all have to band together and take sides. Take, for example, if India and China were to go to war. Pakistan may side with China because they're allies and take it as an opportunity to claim Kashmir. Russia would want to protect its borders and drag in Europe. Eventually the US would intervene too and viola! World war. And yes, this scenario is from Prison Break but it is interesting ;) although they explain it better than I can xD

I had a feeling you watched prison break

My government explained this to me today, but the world is, theoretically, at "economic world peace". All of the countries are so economically bound to other countries, so a war would completely ruin any trading or buying. Countries like the USA or China or other big countries would choose not to officially declare war due to the risk of losing trade partners. My teacher said thats a major factor in why we haven't officially declared war against Afghanistan or wherever the major terrorist groups are.

Good point taratheartist! I was going to say no one declares war anymore.