Most rights afforded to criminal defendants stem from amendments to the United States Constitution. They cover general fairness and the manner in which the government must conduct trials.
Due process is a term that essentially means procedural fairness.
You must be given notice of the charges being brought against you and a legitimate opportunity to contest those charges. In addition, any punishment you receive must fit the crime. The right to notice of the accusation. Defendants have the right to be informed of the nature and cause of any criminal accusations so they can defend themselves. The right to an attorney.