A. Many centre around practical needs - getting meat out of fire, speed, using whatever is around.
B. There are also many superstitions attached to them: dropping chopsticks is bad luck, sticking them upright in your rice is taboo because of the imagery of incense sticks at funeral altars.
C. Among the favourite customs are using them to fish cooked bits of meat and vegetables from boiling broth while eating "hot pot" with friends, and serving choice pieces to show affection or respect.
D. Then there is the long list of chopsticks don'ts: don't point with them, don't spear food with them, don't use them to tap your bowl; only beggars do that.
E. There are many stories of the provenance of chopsticks, which in some form have been entrenched in Chinese history for thousands of years.