A kilogram (kg) is a unit of mass in the metric system, commonly used around the world. It is defined as the mass of a specific physical object known as the International Prototype of the Kilogram, which was made of platinum-iridium. One kilogram is equivalent to 1,000 grams, making it a convenient measure for everyday items like food and household goods. Kilograms are widely used in science, industry, and daily life. For example, when you buy fruits or vegetables, their weight is often measured in kilograms. This unit helps ensure consistency and accuracy in measurements, facilitating trade and communication globally.