What exactly is clean eating ?

I've heard of clean eating before, but I'm not exactly sure what it means. Is it the same thing as eating healthy ? Are there certain foods that you're not supposed to eat when you're "eating clean"? 

it just means sticking to foods that are as unprocessed as possible.  for some people this means only organics, but that's not practical for most of us.

one of the best guidelines out there is the perimeter shopping rule: the least-processed foods tend to be around the outside of the grocery store (bread, fresh produce, fresh meats, and dairy) while the aisles tend to be full of canned and frozen stuff, stuff with long shelf lives, straight-up junk food, etc.

the bulk section can be great too, though, for whole grains, legumes, nuts and seeds, etc.