What is APOKRIES?

Well last day I was chatting with a friend from Greece, I asked her to told me something about her country, traditions, customs, etc.
She told me about the carnival, there is called APOKRIES, well this celebration take place during two weeks, beginning from Sunday or meat fare, and ends with the first day of lont (clean Monday).
The carnival takes place in streets, throwing coloured confetti
The carnival is believed to come from paganism or from old festivities worshipping DIONYSUS (good  wine)