ObjectsArtifact
Portkey
A Portkey is an ordinary object bewitched to carry whoever touches it to a set place at a set time, or when it is triggered. The Weasleys reach the Quidditch World Cup by an old boot. A trophy cup in the maze is a Portkey that takes Harry and Cedric to the graveyard.

First mention
Harry Potter and the Goblet of FireChapter: The Portkey
Arthur Weasley explains the boot on Stoatshead Hill, and the family is pulled to the campground when the appointed time arrives.