– Definition: The foot is a unit of length traditionally used in the imperial and US customary systems of measurement. It is approximately equal to 0.3048 meters or 12 inches.

– History/Origin: The foot has ancient origins, with various cultures using different definitions based on human body parts or natural phenomena. It was standardized to its current length in medieval England.

– Current Uses: Although most countries have adopted the metric system, the foot is still widely used in the United States and the UK for everyday measurements, real estate, and construction.

– Where to Use: Foot are commonly used in architecture, construction, surveying, sports, and real estate. They provide a convenient unit of measurement for distances and dimensions in these fields.

– Definition: The span is a unit of length traditionally used to measure the width of a human hand, from the tip of the thumb to the tip of the little finger when the hand is fully extended. It is typically around 9 inches or 22.86 centimeters.

– History/Origin: The span has ancient origins, with different cultures defining it based on the size of a human hand or the width of a palm. It was commonly used in tailoring, carpentry, and construction.

– Current Uses: While less common than meters or feet, spans are still used in some countries for estimating body measurements, fabric lengths, and architectural dimensions. They provide a convenient unit for measuring small distances and dimensions.

– Where to Use: Spans are employed in tailoring, garment manufacturing, carpentry, and woodworking. They are particularly useful for estimating the size and proportions of objects based on human anatomy.