Prophecy

A Prophecy is a prediction made by a Seer. It can be stored in a spun-glass object, usually referred to as a Prophecy, which is used to record it.

Making a Prophecy
The Seer starts reciting a Prophecy involuntarily. When the Seer is telling a Prophecy, he or she goes into a trance-like state, and speaks in a strange voice. The Seer appearently doesn't remember making Prophecies. The only thing they appear to remember is that they suddenly became very tired. After the Prophecy is made, Seer has the feeling he/she dozed off for a little while.

Known Prophecies by Sybill Trelawney
"It will happen tonight… The Dark Lord lies alone and friendless, abandoned by his followers. His servant has been chained these twelve years. Tonight, before midnight … the servant will break free and set out to rejoin his master. The Dark Lord will rise again with his servant's aid, greater and more terrible than ever he was. Tonight … before midnight … the servant … will set out … to rejoin … his master…"

- Sybill Trelawney telling Harry Potter her second prophecy

Only two known Prophecies have been made by Sybill Trelawney, one to Harry Potter in 1994, foretelling Peter Pettigrew's escape to his master. "The one with the power to vanquish the Dark Lord approaches. … Born to those who have thrice defied him, born as the seventh month dies … and the Dark Lord will mark him as his equal, but he will have power the Dark Lord knows not … and either must die at the hand of the other for neither can live while the other survives. … The one with the power to vanquish the Dark Lord will be born as the seventh month dies…"

- Sybill Trelawney first prophecy

The other Prophecy was told to Albus Dumbledore in 1980, foretelling the birth of a boy who would be capable (though not assured) of defeating Lord Voldemort, that the Dark Lord himself will "mark him as his equal", and that either the boy or Voldemort will ultimately kill the other. This boy was Harry Potter. He was completely unaware of the Prophecy until Dumbledore told him about it after the Battle of the Department of Mysteries.

Ministry of Magic's records
Prophecy Record

The Battle of the Department of Mysteries
Harry had a vision planted in his mind of Sirius Black being tortured by Voldemort to get the prophecy. This drove Harry, Ron, Hermione, Neville, Ginny and Luna to come with Harry to the Ministry of Magic. They used Harry's dream to guide them to the Hall of Prophecies. This is when Ron found the Prophecy with Harry's name on it. It read:

S.P.T to A.P.W.B.D

'Dark Lord  and (?)Harry Potter'

After being chased again the Department of Mysteries for the Prophecy by the Death Eaters, the Prophecy eventually smashed when Neville accidentally kicked it.

Behind the scenes

 * In the Harry Potter and the Order of the Phoenix (film), you hear an echo of the prophecy told by Sybill Trelawney while Harry is holding it.
 * Also in the film; instead of the Prophecy breaking when Harry's holding it, Lucius Malfoy breaks it by dropping and smashing it.
 * In the game version of Order of the Phoenix, the prophecy is destroyed when Harry gives it to Sirius, who deliberately drops it.
 * In the Harry Potter and the Order of the Phoenix (film), the prophecy concerning Harry and Lord Voldemort is shortened from that made in the book. In the film, the last line of the prophecy, which reads "...the one with the power to vanquish the Dark Lord will be born as the seventh month dies...," is excluded.