A symbol is something which as well as being itself also stands for something else, eg the Union Jack flag is an object made of wood and cloth but it is also a symbol of Britain. Symbols can be objects, characters, settings or colours and can symbolise more than one thing at once.
Where and how does Golding does Golding use symbolism in Lord of the Flies?
As a text which is an allegory, Lord of the Flies contains many things which are symbols and have a wider, deeper meaning. Here are some examples:
Ralph discovers the conch shell but it is Piggy who thinks what can be done with it. The conch summons the whole group together and, for a time, helps the boys to unite under one leader and have a single organised plan. As Jack breaks away from the group he refuses to see the conch as the powerful symbol it once was. Towards the end of the novel Piggy desperately clings on to the conch and at the moment when he is killed the shell is shattered. This symbolises the destruction of the qualities it has come to represent.
Piggy is the rational thinker of the group and his glasses suggest that he is able to see what to do. Once the glasses are broken Piggy's powers decline and by the end of the novel Piggy is virtually blind. The glasses are also used to create fire and, for a while, become the most powerful object on the island. Once Jack and his tribe steal Piggy's glasses that power falls into the wrong hands and leaves Ralph's more civilised group in a hopeless situation.
Fire is first used to try to attract a passing ship which would take the boys back to civilisation. The boys keep the signal burning and their hopes alive. Then it is left to go out and this takes their hopes with it. When the first fire gets out of control, destruction follows and several of the smaller boys go missing - we presume they have died. Jack eventually steals fire but this is not for signalling for rescue - it is so his tribe can cook the carcass from the pig hunt. A ship does eventually see the smoke from a fire and comes to rescue the boys. However, this is smoke from a destructive use of fire - Jack's tribe are trying to smoke Ralph out of hiding so that they can kill him.
Apart from the naval officer at the end of the novel the only adult to appear in the story is the parachutist. However as he is dead he can be of no use to the boys - in fact he becomes a symbol of terror to them when Sam amd Eric mistake him for the Beast. The parachutist lands on the island as result of an aerial fight in the adult war that is going on in the wider world. The boys mirror the global events by starting a war of their own.
Other symbols include: Jack's mask and war paint, the hunters' spears, the pig's head, Castle Rock and the scar left by the plane crash.
Why does Golding use symbolism in this way?
Lord of the Flies is not simply a story about a group of boys stranded on a desert island. It is a much deeper allegory that makes points about the world in general. To help his readers to a better understanding of this deeper meaning, William Golding uses symbolism to get his message over to us.