Pandora's box is a legendary accursed artifact, taken from the myth of Pandora's creation. The "box" was actually a large jar given to Pandora, which contained all the evils of the world. Pandora opened the jar and all the evils flew out, leaving only "Hope" inside once she had closed it again.
In mythology, Pandora was the first woman on Earth. Zeus ordered Hephaestus to create her. So he did, using water and earth. The gods endowed her with many gifts: Athena clothed her, Aphrodite gave her beauty, Apollo gave her musical ability, and Hermes gave her speech. However, when Prometheus stole fire from heaven, Zeus took vengeance by presenting Pandora to Prometheus' brother Epimetheus.
Zeus’ final gift to Pandora was a box, one she was warned not to open. Being human with a gift of curiosity, she could not resist the temptation. This lead to a terrible discovery. The box contained every possible evil that could harm and plague mankind. Pandora opens a jar containing death and many other evils which were released into the world. A distraught Pandora tried to close the box before these forces escaped, but she was too late and evil flew out into the world. It is said that the last thing to remain in the box was Hope, before Pandora cried black acid from her eyes because of the wrong she had committed.
According to Athena, Pandora's Box contains the Evils of the world, possibly created in the wake of the Titanomachy. Exactly what this means is never truly explored, but this does not appear to encompass all of the world's flaws; ample amounts of anger, cruelty, and other negative traits are apparent in humanity. However, Hephaestus claims that the Evils within the box could destroy the world if left unchecked, implying that the powers within Pandora's Box may be extremely potent versions of natural negative traits, focused to unnaturally destructive levels by the widespread violence of the Titanomachy.