Final answer:
The invisible line that type sits on is called the baseline, which is essential for aligning text and plays a significant role in graphic design and the arts.
Step-by-step explanation:
The name of the invisible line that type sits on is the baseline. When scribes in the past worked on parchment, they relied on horizontal guidelines to position their writing consistently. The baseline is a fundamental visual tool used not only for the organization of text but also is crucial in graphic design and the arts. It provides the reference line upon which all the characters of a font sit. This ensures that the text is aligned in a straight line and appears orderly. In addition to serving as a textual foundation, lines in art can be used to outline shapes, show motion, convey emotion, and create forms.