Introduction
Taraka, or Tarakasura, is an Asura who obtained a boon that he could be killed only by a son of Shiva, and who terrorised the gods on the strength of it, since Shiva at that time had withdrawn from married life after the death of Sati.
This article follows the Puranic tradition. Where a detail differs between texts, the article says so.
The boon and the threat
Because Shiva showed no interest in marrying again, the gods believed Taraka's condition made him effectively unkillable, and he conquered heaven and drove the gods from their positions.
The birth of Kartikeya
To end Taraka's reign, the gods arranged, with Kama's help, to draw Shiva out of his meditation and toward Parvati, whom he eventually married. Their son, Kartikeya (Skanda), was made commander of the divine army specifically to fight Taraka, and killed him soon after his birth, in the standard Sanskrit Puranic version of the story.
Taraka and Surapadman
In Tamil Shaiva tradition, particularly the account followed in the Kanda Puranam, the demon whom Murugan (Kartikeya) fights and kills is chiefly Surapadman, in a considerably longer and more elaborate war; Taraka appears there as one of several Asura commanders, with the Sanskrit and Tamil traditions differing in emphasis and detail rather than telling exactly the same story.