Micronutrients are essential elements needed by life in small quantities.
They include microminerals and Vitamins.
Microminerals or trace elements include at least iron, cobalt, chromium, copper, iodine, manganese, selenium, zinc, and molybdenum.
They are dietary minerals needed by the human body in very small quantities (generally less than 100mg/day) as opposed to macrominerals which are required in larger quantities.
Note that the use of the term "mineral" here is distinct from the usage in the geological sciences.
Vitamins are organic chemicals that a given living organism requires in trace quantities for good health, but which the organism cannot synthesize, and therefore must obtain from its diet.