It is believed that Goddess Durga fought with evil for 9 nights and 10 days and finally emerged victorious on Dashami.
True. There are many such stories linked with Vijaya Dasami. It's also believed that on this Day Rama won over Ravan..
Today while watching the TV about the event of Dhasara i came to know that the 10 heads of ravana explained as 10 bad qualities of man having. That is kama,krotha,moha,mada,matsarya,lobha,swartha,anyaya,papa,Ahangara.