Micro-nutrients are nutrients that are required in small amounts daily for essential functions in the body.
The two categories of micro-nutrients are Minerals and Vitamins.
Minerals are basic chemical elements that are required in the body for many functions and processes. Some examples are Iron for energy production, Zinc for immune function, and Iodine for thyroid hormone production (Thyroid hormones are used to control metabolism (energy production rates) in the body).
In total there are 14 minerals that are considered essential and some others that are considered required under certain circumstances.
Vitamins are the second category of micro-nutrients. These are chemical compounds that are deemed essential for many functions in the body. The body cannot make / synthesise these compounds itself and relies solely on what is in the diet. In total there are 14 vitamins.