Ink is a gel, sol or solution that contains at least one colourant, such as a dye or pigment, and is used to colour a surface to produce an image, text, or design. Ink is used for drawing or writing with a pen, brush, reed pen, or quill. Thicker inks, in paste form, are used extensively in letterpress and lithographic printing.
Liquid (not blood), that inklings like to use to attack each other until they explode, for no fucking apparent reason. It's also used for writing, but since the rise of the internet, people want to type instead nowadays.