The histogram is really useful in judging your exposure. And yes, no two histograms are ever the same. Basically, you don't want your highlights blown and shadows crushed bcoz' you'll lose detail in your image.
Let's use this image for example. I'll look at the scene and evaluate the light first. The sun is behind me lighting up the pier but, you also see shadows under the pier. Now, I know for sure that I don't want to lose detail in the highlights. Can you tell me which is the brightest part of the scene?

I would say the water or sand area...









Its lunch time and I've got nothing for lunch except these photos 






