Goblet of Fire
The Goblet of Fire is a very old magical object with powerful properties. Detailed description of its appearance in the Harry Potter books can be found at the HP Wiki.
Description & Use
The goblet is made of wood and etched with Runes. When awoken, blue fire rises from its cup. The Goblet's use in the Tournament consists of receiving names submitted on paper and then producing Champions when called for. The champions the Goblet chooses are then entered into a powerful, binding magical contract that requires them to participate in the Tournament.
History
The origin of the goblet is unknown. It has been used as an "impartial judge" for at least two Wizard Tournaments. Once in 1994 and again in 2008.
Ownership
The goblet is currently possessed by the Ministry of Magic's Department of Games and Sports. It is kept there in a jeweled casket when not in use. However, in 2008, the goblins of Gringotts Bank disputed the Ministry's claim to it. See Claiming the Goblet
What Is Known
According to annals of the Ministry of Magic's archives, there is "no evidence that the goblet is goblin-wrought", however there is no evidence that a thorough examination has ever been required nor conducted.
The exact details of the Goblet's powerful magic is also unknown to any documentation available to the Ministry of Magic. What is known is stated above - it's ability to judge the character and suitability of candidates for a task, and the ability to create a binding magical contract.
Once, in 1994, it was discovered that a very powerful Confundus Charm was able to dupe the Goblet.