Ink

Ink is a liquid containing dyes. When it is used, it produces images and texts on various surfaces.

Ink is used in conjecture with quills to write on parchments by wizards and witches in the wizarding world, in place of pens and pencils. There are several types of inks, such as Azul Marino ink and Colour-Change Ink.

Peeves would sometimes shoot ink pellets at Hogwarts students.

Behind the scenes

 * In "The Black Lake" level of Lego Harry Potter Years 1-4, as Harry Potter and Cedric Diggory swim through underwater tunnels, the Giant Squid cuts through the rock and releases ink, forcing Harry and Cedric to use Lumos Solem to find their way to the end of the tunnels.