Napkin etiquette rules are an essential part of table manners, whether you're at a formal dinner or a casual meal. The first rule is that you should unfold your napkin as soon as you sit down. However, if it's a large dinner napkin, you should fold it in half with the fold facing towards you.
During the meal, use your napkin to gently blot your mouth as needed, avoiding any sort of rubbing motion. If you need to leave the table temporarily, you should place your napkin neatly on your chair, not on the table.
When the meal is over, the napkin should be loosely folded and placed to the left of your plate. It's important not to refold your napkin, crumple it up, or leave it on your chair.
Remember, the purpose of the napkin is to keep you clean and tidy, not to clean up spills on the table or to serve as a handkerchief. Following these etiquette rules for napkins will ensure you maintain decorum during any dining situation.