In one sentence, describe what the following article is about:

It's important to understand what a square foot is so you can use your body to draw out an imaginary square foot. A square foot is basically a square that's 12 inches (30.5cm) on each side. To measure the approximate square footage of a space, you measure the length and width of a space. Then, you multiply the numbers to get the total square feet. For example, a table that's 4 feet (122cm) by 3 feet (91cm) would be about 12 square feet. Rooms in odd shapes, however, often have special considerations to take. These calculations are to help you roughly picture or estimate square feet and shouldn't be used to give an exact value. If you don't know the rough measurements of your hands, feet, and other body parts, you probably know your height. You can use your height to approximate square feet in a space. If you need to estimate your apartment's precise square feet, you can lie down against the walls to measure the length and width. For example, if you're six feet tall, and you can lie down twice along the shorter wall of your apartment, its width is 12 feet (3.7m). If you can lie down four times along the longer portion, the length is 48. Multiply the numbers to get approximately 576 square feet. You can also try measuring the space between steps in your stride. You can lay a measuring tape of the floor to get a sense of the length between your strides. If you're trying to measure room space, you can walk along the wall and see how many strides you can take to measure the length and width of a room. If you average about a foot between strides, and can make 15 strides along one wall and 12 along the other, the rough length and width of the room is 10 by 5. Multiple this to get 180 square feet. A lot of people know the length of their feet off-hand. If you've ever had to measure your feet at a shoe-fitting, and remember their length, these can be used to picture or estimate square feet. Say you're buying an end table that will allegedly take up 3 square feet. You can't know the exact length and width, but for a rough idea of how much space the table will take, imagine a table that's 1.5 feet (0.5m) wide and 1.5 feet long. If your feet are 9 inches (22.9cm), that's about two of your feet for either side of the table. If you're measuring very small objects, you can use your hand as a guide. If you know the rough measurement from the tips of your fingers to your palm, you can place your hand along the side of objects to get a sense of their rough square footage. If you're measuring an end table, for example, say you can fit three hands along one side and three hands along the other. Your hands are about six inches each, making the table 1.5 feet (0.5m) by 1.5 feet. It takes up about 3 square feet of floor space.

Summary:
Multiply length and width to calculate square feet. Use your height to visualize square feet. Measure your stride. Try measuring with your feet. Use your hand to measure smaller objects.