In the Zone diet, "good" and "bad" are defined by how quickly they break down and do they give you an insulin surge, and then the "crash" afterword.

Good carbs are those that take longer to process and give you a more sustained energy rather than a quick burst followed by the crash. It's not always obvious, but in general starches (potatoes, flour, sugar) are fast, some fruits are fast, but other fruits and veggies aren't.

Black beans - good. Brown rice - better than white rice, but not as good as steel cut oats. Rye flour/bread - better than white.

So essentially we got most of our carbs from fruit and veggies, and fewer from processed foods, sugar, starches.

In the Zone, you also ate protein and fat as part of every meal and snack, so that your "fuel" was balanced with all, not too heavy in any one direction.

As others have said, the definition depends on the resource, I think.