What was the Index of Forbidden Books, and is it OK to read those books now?

The Index was a list of books considered dangerous to faith or morals. In establishing the Index the Church intended to protect Catholics from such material. The subject matter of books listed on the Index ranged from heretical treatises to pornography. After Vatican Council II a specific list of books was dropped and a set of guidelines established in its place. The reading of such books is not edifying spiritually or morally. They should not be read out of curiosity. Permission to read objectionable books is given to those whose task it is to refute them and defend the teaching of the Church.