A "metric" is a standard unit of measurement used to quantify various attributes, such as length, weight, or volume. The metric system is based on powers of ten, making it easier to convert between units. Common metric units include the meter for length, the kilogram for mass, and the liter for volume. Metrics are widely used in science, engineering, and everyday life because they provide a clear and consistent way to communicate measurements. The system is used globally, with the exception of a few countries, and is essential for international trade and collaboration in fields like science and technology.