Piggy is an overweight, asthmatic boy who wears glasses. He is intellectual and not very good at physical labor. He is around 12 years old and looks more mature than the other boys. For example Piggy does not have much hair, and after being on the island, his hair does not grow very much. He looks and acts like an old man.
Piggy holds onto the idea of the rituals of home longer than the other boys. He likes to think about what grown-ups would do in different situations. He treasures any representation of civilization that can be created on the island.
"It is Piggy who not only recognizes the significance of the conch but whose spectacles enable Ralph to start the fire, whose smoke is their only chance of being saved."
"It is Piggy who realizes that building the shelters is at least as important for their long-term survival as keeping the fire going."
Even though Piggy is smarter than most of the boys, he is not respected by the group for his ideas. He has no power in the group, he struggles to be heard by the other boys.
He is important in the novel because he represents the side of civilization, as the voice of reason, that the author pits against savage instinct in the book, as represented by Jack and the hunters.