What refers to an upright structure that serves to commemorate an individual at a burial site?

The term that refers to an upright structure designed to commemorate an individual at a burial site is a headstone. A headstone typically includes the deceased's name, dates of birth and death, and sometimes additional information or inscriptions that reflect the person's life or beliefs. It serves both a practical purpose—marking the grave—and a memorial function, allowing loved ones to remember the individual.

While an obelisk can also serve as a monument, typically taller and often associated with more grand memorials or monuments rather than individual graves, it is not exclusively designed for that purpose. A plaque is usually a flat piece used for memorials but is not upright, and a statue, while it can commemorate an individual, is more commonly used for larger memorials or public spaces rather than specifically marking a burial site. Thus, the headstone is the most direct and conventional choice for marking a grave.