The thyroid, a small endocrine gland located in the neck, plays a crucial role in regulating the body's metabolic processes. It produces the hormones thyroxine and triiodothyronine, which are essential for the normal functioning of the body, and their synthesis involves a complex process of iodine uptake from the blood and a series of biochemical reactions. The regulation of the thyroid function depends on the interaction between the hypothalamus, pituitary gland, and the thyroid itself, with thyrotropin playing a key role in stimulating hormone production. Disturbances in thyroid function in the form of hyperthyroidism or hypothyroidism can lead to serious health problems, whether caused by autoimmune mechanisms, such as Hashimoto's thyroiditis and Graves' disease, or other causes. Environmental factors and lifestyle habits can significantly impact thyroid function. Exposure to chemical compounds such as pesticides, triclosan, and perchlorate, as well as heavy metals, can act as endocrine disruptors, interfering with normal thyroid function. Pesticides can affect hormone synthesis, while heavy metals can be toxic at higher concentrations. Additionally, lifestyle habits such as smoking, alcohol consumption, and poor diet can increase the risk of thyroid diseases. Furthermore, the impact of diet, lack of physical activity, stress, and medications also influences thyroid function. A diet rich in iodine, as well as certain ingredients in different foods, can alter thyroid hormone levels. Physical activity and stress can also affect thyroid function, while certain medications can trigger autoimmune thyroid diseases. Understanding and managing these factors can reduce the prevalence of thyroid diseases in the population.