What defines something as a micronutrient?

Micronutrients are essential nutrients required by the body in small amounts for various physiological functions, including growth, metabolism, and disease prevention. They primarily include vitamins and minerals, which play critical roles in processes such as immune function, bone health, and energy production. Unlike macronutrients, which provide energy and are needed in larger quantities, micronutrients are vital for maintaining health and preventing deficiencies, even though they are needed in microgram or milligram amounts.