A gram is a unit of mass in the metric system, commonly used to measure small quantities of substances. It is defined as one-thousandth of a kilogram, which is the base unit of mass in the International System of Units (SI). Grams are often used in cooking, science, and nutrition to quantify ingredients and materials. In everyday life, grams are frequently seen on food packaging to indicate serving sizes and nutritional information. For example, a nutrition label might show that a serving of cereal contains 30 grams of carbohydrates. This helps consumers make informed choices about their diets and portion sizes.