Net etiquette or "Netiquette" refers to the proper and respectful use of the internet. The guidelines for good net etiquette include:
- Be Ethical (A): Following ethical standards online.
- Respect Privacy (B): Ensuring others' privacy is respected.
- Be Responsible (C): Taking responsibility for one's actions online.
- Be Respectful (D): Treating others with respect in all online interactions.
Thus, the correct answer is "A, B, C and D."