A square foot is a unit of area measurement commonly used in the United States and other countries that follow the imperial system. It represents the area of a square with each side measuring one foot in length. This measurement is often used in real estate, construction, and interior design to describe the size of rooms, buildings, and land. To calculate the area in square feet, you multiply the length by the width of a space, both measured in feet. For example, a room that is 10 feet long and 12 feet wide has an area of 120 square feet. Understanding square footage is essential for determining space requirements and costs in various projects.