The types of diversity include race, religion, gender, age, ethic group, cultural, nationality, sexual orientation, social class, geographic region, and physical challenges.
Sadly we live in a world that's never going to see "change". Yes, we've come along way form out past history and managed to accept that we're all humans and have the same rights as the next man/woman. Unfortunately, not all of us agree on the concept of equality especially in business etiquette and ethics. Us, human beings, lack the full intelligence to fathom and comprehend that we all bleed red, need food, shelter, love, and faith to make it through day to day. In my opinion, discrimination exists from the 3 of the deadliest sins: Envy, Greed, and Lust.
Envy because we don't want others to succeed, have what we have/want, and be above us in terms of education, employment, and social status.
Greed because, as human nature has it, we want everything for ourselves. The hardest thing for a human to do willing is to share: wealth, happiness, health, currency, and well being, Some of us are good willed by nature but it's rare to come across someone who's willing to share everything they have with someone they just met or been knowing, hell, even one's own family.
Lust because some of us want to feel dominant, whether it's an sexual manner or social status manner. We want to ecstasy feeling of feeling superior above someone else and have full control and what better way than to limit a human being by their: sex, age, ethnicity, religion, backgrounds, etc.
Humans get off on the fact of being a lustful, envious, and greedy mammals that want everything the world has to offer for any price we're willing to pay.