Ravana was the king of demons and the ruler of Lanka. He had
ten heads and twenty arms. Ravana was a great devotee of Lord Shiva and
had been granted many boons by him. Brahma had also granted him a boon by
which he could not be killed by any god or demon. However, Ravana forgot
to ask for protection from men or animals.
Ravana was blessed with many supernatural powers such as flying and
becoming invisible, but this also made him very proud. He misused his
powers and the gods felt it was necessary to destroy him. Since only a
human could kill Ravana, Lord Vishnu incarnated himself as Rama, prince of
Ayodhya. With the help of an army of monkeys, Rama went to Lanka and
killed Ravana, symbolising the triumph of good over evil.