Which of the following defines square footage?

Square footage refers specifically to the area measurement of a space and is measured in square feet. To accurately calculate the square footage of a rectangular or square space, one must multiply the length by the width. This formula provides the total area, expressed in square feet, which is essential for various applications, including real estate, construction, and flooring projects.

In this context, the other options do not correctly represent the definition of square footage. Measuring volume in cubic feet pertains to three-dimensional space, which is not relevant when calculating flat area. Adding length and width does not yield an area measurement but rather provides a linear dimension. Lastly, perimeter refers to the total distance around a space, also not applicable for determining area. Thus, the correct choice emphasizes the multiplication of length and width to derive square footage, making it the best definition.