Definitions: (1) the forms, manners, and ceremonies established by convention as acceptable or required in society, in a profession or in official life; mannerly; (2) an appreciation of superior thought or behavior

• Nothing is less important than which fork you use. Etiquette is the science of living. It embraces everything. It is ethics. It is honor. — Emily Post (1872–1960) American author
• Emotional intelligence is your ability to recognize and understand emotions in yourself and others, and your ability to use this awareness to manage your behavior and relationships. — Dr. Travis Bradberry (1976-) American author

Comment: This is one of the qualities that involves the doing as well as the not doing. Etiquette includes not doing certain things in public as well as doing other things when appropriate. Knowing what is appropriate is the whole trick.