A pen is a common writing instrument used to apply ink to a surface, usually paper, for writing or drawing.
Historically, reed pens, quill pens, and dip pens were used, with a nib dipped in ink.
Ruling pens allow precise adjustment of line width and still find a few specialized uses, but technical pens such as the Rapidograph are more commonly used. Modern types include ballpoint, rollerball, fountain, and felt or ceramic tip pens.