Here is a chart that explains it very well. It is also called the Caveman's Diet. Primal is another name that's used. I'm not interested in their philosophy, but this way of eating fits in fairly well with what I'm doing. Not all Paleo recipes are dairy free and grain free, but many of them are. I think some people just aren't ready yet to go there yet. What I like about it is that they use whole foods and aren't afraid of good fats. They eat a lot of meat and don't do that much baking. It's meat and veggies which is what I'm suppose to be eating.
Here are a couple of blogs here Mastering the Art of Paleo Cooking and here The Food Lovers Primal Palate. I got their cookbook out of the library and it was pretty good.