Being discriminated against at work means that you are being treated differently than other people because you are in a particular class that is a protected class. That would be, you are being discriminated against or treated differently because of your sex, because of your religion, because of your race, because of your color, because of your age or disability, or your veteran status. Those are protected classes and if you are discriminated against because you are in one of those classes, you have certain rights.
