I'm a professional horse racing handicapper.
and I'm a degenerate gambler. what a coincidence. I do love that equestrian performance sport.
When was horse racing invented?
It's the most ancient of all sports . It has been around since time started and the sun started to rise in the sky. 
How much money is generated from gambling on horse racing?
More then you can imagine. In 2008 alone it generated over 115 billion. Yes billion. You must be rolling in the money with your handicapping skills. 
You know it. Are there different types of horse racing?
Horse racing
Horse racing is an equestrian performance sport, typically involving two or more horses ridden by jockeys (or sometimes driven without riders) over a set distance for competition. It is one of the most ancient of all sports, as its basic premise – to identify which of two or more horses is the fastest over a set course or distance – has been unchanged since at least classical antiquity.
Horse races vary widely in format and many countries have developed their own particular traditions around the sport. Variations include restricting
in the stretch and won by one and three quarter lengths from Flexibility despite drifting to the right in the closing stages. McLaughlin commented "We were a little worried about the kickback, how he would break, and the others that have had more racing experience than him. But he's a very talented horse and I'm glad he lived up to the betting public's odds". Alvarado reported that the colt had been uneasy in the starting gate but that when the race started "all I tried to do was not