As so many people have said, good and bad aren't physically real. They're abstract. Even so, they're relative. Peoples ideas of both good and bad change depending on perspective, time, context. People have different ideas but, as BoB said, basically, if it hurts other people then it's bad. If it helps people it's good. That becomes more complicated, though, when you have something that helps some but hurts others. And it too cahnges depending on perspective and things.

Giving good and bad a set place is just something that builds a plot for crappy stories. Same for evil. Evil doesn't exist. Evil cannot be good. Ever. That's what makes them evil (which really isn't fair. They're bad because it's all they can be, but then it's not their fault. They can't be anything else. Except for different levels of smug). Everybody has the capability of being kind or 'good', as in helping others. Some people just don't. 'Cause they're jerks
Some people are just jerks...