Kali appeared for the first time to defeat the evil demon Raktabija. Raktabija was on a path of destruction in the heavens and on earth. Each time an attempt was made on his life, his drops of blood transformed into additional Raktabija demons. So, Kali descended and began to destroy the Raktabija demons. She utilized her long tongue to catch the Raktabija blood, thus not allowing for the generation of additional demons. In the end Kali was successful and ended the wrath of the Raktabija demons. However, the extreme amounts of Raktabija blood she had to intake in the process caused her to rampage. She consequently crossed the universe killing anyone who came across her path. Lord Shiva is often shown behind the right foot of Kali - It is done as Lord Shiva stopped Kali by lying himself in her way to calm down the extreme anger of Kali and thus protected the world from the devastating power of Shakti.
Kali is a form of goddess Durga. Because of her destructive behavior Kali is sometimes referred to as the goddess of time and death. She is often depicted with dark skin to symbolize the darkness of eternity and dark, messy hair to symbolize the dark clouds of the eternal sky. A necklace of skulls is often shown around her neck symbolizing death and destruction. Many times she is depicted with a severed head in her bottom left hand to show that there is no escape from time.