Taboo means forbidden, though not necessarily 'evil'. Taboos are social norms, often preventative in nature. For example, the Western society taboo against cannibalism.
A mark of differentiation between civilized countries and primitive tribes is that the religions of the former explicitly require and forbid what is good and evil. For example, the Judeo-Christian tradition has the Ten Commandments. In primitive cultures, a taboo is often tacit.
Some anthropologists who promote cultural relativism have sought to introduce 'uncivilised' practices into 'civilised' society. The increasingly liberal National Geographic magazine (and especially its televised documentaries) take this approach.
Taboo is a topic often discussed by moralists, ethicists, theologicans and sociologists. Also to know conservative and liberal activism has its own rules, core beliefs and taboos they take very seriously.