Ganesha, also called Ganapati, is the god of wisdom, prudence, and salvation. Ga means "knowledge", na means "salvation", and isa and pati means "lord". Ganesha is also said to mean 'lord of the ganas', Shiva's multitude of attendants. In south India, Ganesha is worshipped as Pillaiyar. Ganesha is represented as a short, pot-bellied man with an elephant's head with one tusk, four arms, and yellow skin. In mythology, the elephant symbolises devotion, patience and truth. His corpulent figure conveys prosperity as represented by the laddoos he is always shown with. In his hands, he holds a conch shell, a discus, a club, and a lotus. Ganesha rides on a mouse, signifying the unity of the small with the big. He is also the most widely worshipped deity. All ceremonies, religious or secular, begin with an invocation to Ganesha. His image is printed on cards sent out for any happy occasion. Usually before beginning any religious writing, he is invoked with words 'Aum Shri Ganeshaya Namaha', literally meaning "Ganesha, I pray to you". Most people, from student to shopkeeper, movie producer to nuclear scientist, begin work by invoking Ganesha, however briefly. The Puranas differ considerably in their account of Ganesha's origin.

He is not mentioned before 500 AD and was quite insignificant until the mid-15th century. According to the Padma Purana, he is the younger son of Shiva and Parvati. According to the Shiva Purana, Ganesha was born of the scurf from Parvati's body. Once, when Shiva was away, Parvati wanted someone to guard the door while she bathed. Ganesha from the scurf of her body, she moulded a boy and gave him life. She told him to attend the door and not allow anyone to enter. Shiva returned, and when he tried to enter, was stopped by Ganesha. An argument arose, and enraged, Shiva cut off Ganesha's head and entered. When Parvati discovered that Shiva had entered by beheading her son, she was inconsolable. Repentant, Shiva ordered that the head of the first living being that was found should be brought to him. This happened to be the head of an elephant calf. He placed this on Ganesha's body and restored him to life. A legend explains why Ganesha is worshipped before any other deity or prior to any important event. It happened that Shiva asked Kartikeya and Ganesha to circle the world and return. Kartikeya hurried off on his peacock, but Ganesha walked around Shiva and Parvati. He explained that for him, his parents constituted the world. Pleased, Shiva granted him a boon, saying that before undertaking any important task, people would pray to Ganesha.

According to the Narasimha Purana, if he is not worshipped at the beginning of a ceremony, he creates obstacles for the performers. Therefore, no matter what the occasion or ceremony be, Ganesha is worshipped before all other deities. For this reason, he is called Vighneshwara, the remover of all obstacles. Ganesha's mouse, by gnawing its way through everything, is said to symbolise the god's ability to destroy all obstacles. Ganesha is believed to have written the Mahabharata to Veda Vyasa's dictation. When the sage asked Ganesha to write down the epic, the learned god agreed on condition that his pen should not stop moving until the story was completed. Vyasa agreed but said that Ganesha should write only if he completely understood what was dictated. So whenever Ganesha stopped to consider Vyasa's complicated compositions, the sage would use the time to compose more verses.

Ganesha is also known as Ekdanta, or the one with one tooth, because one of his tusks is broken. The reason for this, according to the Padma Purana, is that one day when Shiva was sleeping, Parashurama came to visit him. However, Ganesha would not allow Parashurama in, for his father's sleep would be disturbed. When Parashurama insisted he be permitted entry, a fight broke out. In the course of their struggle, Parashurama threw his axe at Ganesha. This axe had been given to him by Shiva. Recognising the axe and out of reverence for his father, Ganesha refused to intercept the weapon. He bowed and took its impact on one of his tusks, which broke. The Puranas say that the fourth day of the month, known as Chaturthi, is specially auspicious for Ganesha worship. It is believed that Ganesha was born on the Chaturthi of bright night of Bhadra (August-september). It is however, considered unlucky to look at moon this night. It is said, once Ganesha was fell off its rat and moon laughed at him. This annoyed Ganesh and he cursed the moon saying that ill luck would befall on anyone who looked at the moon on that night. Lokmanya Tilak revived the observance of Ganesh Chaturthi in Maharashtra where it is worshipped more, for 10 days and on the 10th day procession carrying Ganesh idol accompanied by singing and dancing is immersed in water, this known as Visarjana.

Reincarnated in different yugas in different forms to right wrongs, it is believed that Ganesha will be born again as 'Dhoomaketu' in Kali Yuga, to exterminate the evil and restore peace and harmony.