Trace elements, despite being needed in extremely small amounts, play a crucial role in maintaining physiological functions, growth, and health of organisms. Trace elements, such as iron, zinc, and selenium, contribute to various physiological functions, from immune support to enzyme activity. They have a very important role in the growth and development of the human body. The trace elements are divided into three groups, namely, essential elements, elements which are probably essential, and potentially toxic elements. These components are necessary for a number of physiological functions, such as hormone production, immune system control, enzyme activity, and tissue integrity maintenance. A balanced intake of trace elements through a diverse and nutrient-dense diet is essential to supporting general well-being, even if excesses or deficits of these elements can cause major health issues. This chapter discusses sources and the role of these essential trace elements.