Shiva (Sanskrit for "auspicous one") is one of the predominant Hindu deities. He is the Destroyer or Transformer of the Hindu trinity, also comprised of Brahma the Creator, and Vishnu the Preserver. He can also be known as Nataraja, the "Lord of Dancers", Sambhu "Benign", Samkara "Beneficent", Pasupati "Lord of Beasts", Mahesa "Great Lord" and Mahadeva "Great God", amongst others. He has possibly evolved from the older Vedic Rudra ("Howler"), Lord of the Hunt and of Storms.
He can either be depicted in an abstract form via the shiva lingam, a phallic symbol of the male creative energy, or in human form of a four-armed young man either deep in meditation or dancing the Cosmic Dance.
Perhaps the word "destroyer" is misleading, as destruction in this case leads to better things, clearing the way for the new, leaving by the wayside all that hinders and which is unhelpful or unhealthy. Much like the Death card in the Major Arcana of the Tarot, with death leading to rebirth.
His wife is Pavati (or Shakti), he is the father of Ganesha (remover of obstacles). He is indelibly linked with the Ganges River, when the Goddess Ganga fell to earth, he caught her in his hair, breaking her fall and allowing her to gentle trickle to the ground. He is often depicted with matted hair, piled on top of his head, pouring forth the waters of the Ganges.
One legend describes how Shiva travelled to the dense forests of South India, where there lived a large number of heretical sages. The sages argued amongst themselves, but eventually their ire became focussed upon Shiva. They conjured creatures to destroy him, firstly a tiger summoned from the sacrificial fires. Shiva simply hooked the fierce beast with his fingernail, skinned it and wrapped the hide around himself.
The sages tried again, this time their offerings brought forth a huge serpent. Shiva took the snake, and wrapped it around his neck, wearing it as a garland. Shiva began to dance.
The third and final attempt upon Shiva's life was to bring forth a monster in the form of malignant dwarf. Shiva pressed his foot against the dwarf and broke its back, leaving it prostrate and helpless upon the floor, and continued his dance.
There are many symbols associated with Shiva, some of these are:-
Blue throat/skin - from a time when poison churned in the oceans, Shiva drank the poison and kept it in his throat, where it left a permanent stain.
Third Eye - representing wisdom and insight. This eye is often a source of a fierce cleansing fire, specifically focussing upon evil.
Cobra necklace and tiger skin - representing his mastery over the world's dangerous creatures (and evil), and also the power of destruction and recreation, as snakes are continually shedding their old and outgrown skins.
Trident - representing his powers of will, action and knowledge.
White Bull - the bull is his vehicle, and can represent power and ignorance, and in this context Shiva can be seen to exert his power and destroy ignorance.
Hour-glass drum - beating the rhythm of the universe, and of the dance.