Explain me like I am five, how the hell this chrome profiler works and how do you figure out memory leaks!?

I have read and watched numerous vidoes and stuff but still there is nothing out there solid to explain here is the memory leak with a good example. All they do is a single variable or click handler and take a snapshot. Then see here is our memory usage. Ok I got it but real world apps are not just a single variable or function. If i take my app and take a heap snapshot, there are hundred thousands of those stuff. I did try to go through them but when you are not sure what are you looking for couldn't really make any sense of it. How do you read that snapshot graph and how can I tell, here, because of ...... It looks like there is possibly a memory leak or this event is not cleaning itself. I mean google spends truck loads of money on it and i am pretty sure if I can understand it will help tremendously but i wish there were some more detailed information out there.