A kilogram is a unit of mass in the metric system, symbolized as kg. It is defined as the mass of a specific platinum-iridium cylinder kept at the International Bureau of Weights and Measures. One kilogram is equivalent to 1,000 grams, making it a fundamental unit for measuring weight in many countries. Kilograms are commonly used in everyday life, such as in cooking, where ingredients are often measured in kilograms and grams. The metric system, which includes kilograms, is widely adopted around the world for scientific, industrial, and commercial purposes, providing a standardized way to measure mass.