== What and Why does it exist? == 

 This page is like explaining how a car works without explaining what it is or why it exists. This leads to Anekantavada problem (the three blind men examining an elephant and each will tell you the elephant is something different). What is it? It has some pistons and is powered by gasoline. Yes, but what is it and why did they build it? The gasoline is vaporized and a spark introduced to cause it to explode.  WHAT IS IT AND WHY DOES IT EXIST?!