An Avatar is a representation of a spiritual being
manifested on Earth. Usually the manifestation of a Avatar is to rid the world
of a great evil or to bring a new outlook to the world itself. Its the variable
to balance the equation.
A perfect example would be Narasimha. An avatar of
Vishnu created to destroy an "asura". A power hungry deity. This
"asura" was named Hiranyakashup. Due to harsh penance and
meditation, Hiranyakashup reaped the fruit of his labor. When
Brahma appeared before him and asked him to request his boons. Hiranyakashup
had plans of his own. Throughout Hindu Mythology, "asuras" have
always wanted to conquer heaven and rule the world an gain immortality.
Learning from his caste's mistakes he planned out his request. His wish was
that he could "not be slain in heaven, on earth, in the daytime, at
night, from neither above nor below", neither by man nor animal."
Once Hiranyakashup overthrew heaven and casted out the gods. To justify
his rule, he began hunting the pious devotees of Vishnu who sought to
have Hiranyakashup killed. Descending to earth in the form of
Narasimha, Vishnu appears before the complaisant Hiranyakashipu. As half man (nara)
and half lion (simha), he is neither man nor lion; he springs out of a
pillar; he strikes at twilight, when it is neither day nor light; and he
attacks Hiranyakashipu at the threshold of his palace, under the arch of the
doorway, neither on earth nor in the sky. Narasimha throws Hiranyakashipu upon
his thighs and rips apart his bowels with his claws.
