Shiva is the source of yogic traditions. When an individual practices yoga and achieves union between mind, body and spirit, they achieve harmony with all things; therefore, they experience nothingness because the ego is destroyed.
Lord Shiva is depicted with a third eye on his forehead. The King of Serpents, Vasuki, is coiled around his neck. A crescent moon rests upon his head and the Ganga river flows from his matted hair. He also possesses a trident and a drum in most images.
Parvati is the consort of Shiva. Some say that Maha Shivaratri, a holiday dedicated to Shiva, marks the day that he and Parvati were wed. It is said that when Shiva is reincarted as an avatar, Parvati is also reincarnated as that avatar's consort. The avatar, Krishna, for example, was accompanied by Radha and the two are often worshiped together. Lord Nataraja, the Lord of Dance, is another incarnation of Shiva.
Shaivism (also spelled Saivism) is one of the main sects of Hinduism and refers to those who consider Shiva to be the supreme being. Shaivism has five sub-sects: Shaiva Siddhanta, Kashmir Shaivism, Vira Shaivism, Gorakhnath Shaivism and Pasupatha Shaivism.