Pandora is the sister-in-law of Prometheus and the wife of Epimetheus. After Prometheus stole fire from the gods and gave it to the mortals, the gods sealed all the horrors of the world in a box. It was beyond beautiful: inlaid woods of warm and burnished hues, white and amber diamonds encrusted to border the box, green emeral in plaits of golden leaf, purple amethyst with blood rubies and blue sapphires, along with white pearls gleaming in the extravagant sunlight. They gave it to Pandora as a wedding gift, knowing that she couldn't resist opening it because of her curiousity. Because Hermes gave her deceitfulness, she opened the box. In doing so, she released Hunger, Thirst, Poverty, Murder, Death, Jealousy and many other bad things into the world. Only Elpis, the spirit of Hope remained in the pithos.
The Pithos was given in second titan war it to the olympians by the titans as a mean to signal they're surrender. They're leader Percy Jackson said they would never surrender and gave the pithos to Hestia. Which is where it is now.