Dining etiquette is really important for broader social etiquette. Sharing a meal together is one of the most intimate, fun and relaxing things that people can do together. But there are certain conventions that everyone has to observe so that the meal is a good experience for all involved.
You probably know most of them. Don't eat in a slovenly way, be polite, don't abuse wait staff, be generous and equal with the bill, things like that. But I tend to find that people with bad table manners have bad manners in other aspects of their life. If reveals something about their character.