What fabric square is placed under dining equipment as part of the table setting?

The fabric square that is placed under dining equipment as part of the table setting is typically the napkin. In a formal table setting, the napkin not only serves a practical function but also adds to the aesthetic appeal of the table. It is often folded in decorative ways and can be placed in various positions on the table, such as on the plate or to the left of the forks.

While chargers serve as decorative bases for plates and a tablecloth creates a base layer for the entire setting, the napkin specifically contributes to the individual place setting and is important for personal use during the meal. The other choices, such as the plate setting and tablecloth, relate to different aspects of the table arrangement and do not fulfill the specific role that a napkin does.