Etiquette (noun)

1. The set of conventional rules governing behavior in polite society.
2. A particular type of conventional behavior in a particular social group or situation.

Origin:

Early 18th century: from french étiquette "label, ticket", diminutive of étiquet (see ticket).

Examples:

1. It's important to know the etiquette for a formal dinner.
2. He was unsure of the etiquette for meeting a royal.
3. The etiquette for addressing a judge in court.
4. The etiquette for sending a thank-you note.
5. Proper etiquette dictates that one should not speak with their mouth full.