Weirdness in Black
Ink is a pigmented (and/or dyed) liquid used for writing, printing and drawing on paper (or historically, on parchment).
Ink can have any color. In art, black (or sepia) ink is most common, while in writing, today, black and dark blue are most popular.
Ink in drawing
For drawing, ink can be applied with a pen, a brush, a nib or a quill.
An artist who inks drawings (e.g. in cartoon, comic, and animation) is called an inker.