This legend narrates the story of the birth of Ganesha.

Ganesha the elephant faced God is one of the most popularly worshipped forms of divinity - as a remover of obstacles and the embodiment of good luck, in the Indian system of beliefs and practices.

Ganesha is regarded as the son of Shiva and Parvati (Shakti), the Universal parents, and the brother of Skanda.

Legend has it that Parvati, created a beautiful boy from the dirt of her body, treated him as her son, and gave him the responsibility of guarding her home. Shiva, upon returning home  was affronted by this lad, hitherto unknown to him. The lad, true to his word to his mother, refused to let Shiva into his own home.

An enraged Shiva sent his Bhuta Gana attendants to scare the lad and to obtain entry into his own home. The lad single handedly defeated the Bhuta Ganas in battle. A clash of egos followed, as Shiva sent several of the Gods, to fight against Ganesha and an equally enraged Parvati sent several of her attendants to fight them. In the resultant fight, the valorous lad's head was chopped off by Nandi deva, and the lad lay lifeless.

Parvati's grief knew no bounds, and Shiva sought to assuage her, by promising to bring the boy to life. Alas, his head could not be found in the battlefield. A quick fix was sought, and it was decided that the first available head would be used to bring the boy to life. Accordingly, the boy was fitted with the head of an elephant and brought back to life.

Even this did not placate Parvati, who sought that this boy (who successfully created obstacles to his father's mission) now fitted with the head of an elephant, should be regarded by one and all, as the remover of obstacles, and should be offered worship first, before any form of worship was offered to any other manifestation of divinity.

This boon granted, Ganesha, the lord of the attendants of Parvati, came to be regarded as Vigneshwara the remover of obstacles.

Also See:

Ganapateeswaram where an image of Ganesha with a human face is held in worship
The Vallikalyanam legend where Ganesha created and removed obstacles in the path of Skanda's marriage