Each Purana reports a different story to narrate the birth of the god Ganesha. This version follows the Shiva- Purana.
Goddess Parvathi wanted to take a bath. Having no attendants to guard her and to stop anyone from accidentally entering her abode, she decided to create a boy out of tumeric paste, which she had prepared for her bath. She infused life into her creation and hence Ganesha was born.
Parvathi ordered Ganesha not to allow anyone to enter the house, and Ganesha obediently followed his mother’s orders. The Goddess then proceeded to take her bath.
In this time, Lord Shiva returned and as he tried to enter the house, Ganesha stopped him. Shiva was infuriated at this strange little boy who dared to challenge him. He told Ganesha that he was Parvati’s husband, and demanded that Ganesha let him go in. But Ganesha would not hear of it, saying that he will follow only his mother’s orders.Shiva lost his patience and had a fierce battle with Ganesha.
In his anger, Lord Shiva severed Ganesha’s head. When Parvati came out and saw her son’s lifeless body, she was furious. She demanded that Shiva restore Ganesha’s life at once.
The revenge of Pârvatî was terrible : she created innumerable Shaktis (forms of herself) and ordered them to devour all the Gana (celestial armies) and Devâ (Gods) .
Absolutely terrified, Brahmâ and Vishnu begged for her; in exchange, Pârvatî demanded that her son be revived, She also asks that her son be worshipped first, before all other gods.
Hence, in all Hindu prayers, offerings are done for Lord Ganesha before other gods.
Shiva sends his ganas (celestial troops), ordering them to bring back the head of the first living being lying north – this direction is known to be auspicious and synonymous with wisdom. The first living being with its head turned to the north is an elephant. They bring back its head and Shiva replaces it on the child’s body and he gives him life. Pârvatî is joyous and embraces her son. Lord Shiva then names the boy, Ganapathi- or commander of His troops.
His form:
His vehicle:
According to the Holy Ganeshapurana, Lord Ganesha’s Mouse was actually a god in his own right at one time — his name was Kroncha.
At the assembly of Lord Indra, Kroncha accidentally stepped on the toes of Muni Vamadeva, another god. Muni Vamadeva thought that Kroncha had done so intentionally and grew enraged and cursed Kroncha to become a mouse. Terrified, Kroncha fell to his knees and pleaded for mercy. This subdued Muni Vamadeva’s anger. He said that his curse could not go in vain, but that Kroncha would meet Lord Ganesh and become his vehicle and become worthy of worship even by gods.
And so it was. Kroncha, transformed into a mouse by the curse of Vamadeva Muni and fell into the hermitage of Maharshi Parashar.
Kroncha, however, was no ordinary mouse. In fact, he was as big as a mountain and frightening to all who beheld him. He caused no end of trouble and destroyed everything in his path, just like a mountain-sized mouse could be expected to do.
Lord Ganesha, who was being taken care of by Maharshi Parashar and his wife Vatsala in the hermitage, heard all the commotion and decided to do something this mouse. Ganesha unleashed one of his weapons: a pasha(noose), which he sent flying in the direction of Kroncha. The pasha was so radiant its light filled the entire universe. Pasha chased the mouse and looped around his neck and brought Kroncha to Ganesha’s feet.
Lord Ganesha said: “Kroncha, you have troubled the Sages and Brahmins to no end, but since you ask for forgiveness, I shall use you as my vehicle.”
Whereupon Ganesha mounted Kroncha and hence Kroncha became Ganesha’s vehicle, also known as Mushika.