In J.K. Rowling’s fantasy novel Harry Potter and the Chamber of Secrets, Tom Riddle’s diary opens the Chamber of Secrets.
The diary is a magical object containing a younger version of Tom Riddle, the student who later becomes Lord Voldemort. Ginny Weasley finds it and writes in it, allowing Riddle to manipulate her and use her actions to reopen the hidden chamber beneath Hogwarts.
Riddle’s diary is not an ordinary school journal. It is one of Voldemort’s Horcruxes, an object containing a fragment of his soul. Harry destroys it with a basilisk fang, making it the first Horcrux destroyed in the story.
Readers sometimes connect the Chamber primarily with Salazar Slytherin, who created it, or with the basilisk hidden inside. However, the diary is the specific object that enables Riddle to influence Ginny and initiate the events of the novel.