Anemia is a decrease in red blood cells or hemoglobin in the blood, affecting about a quarter of the global population. Iron deficiency anemia alone affects nearly 1 billion people and was responsible for 183,000 deaths in 2013. Anemia increases healthcare costs and lowers productivity. It has various causes including iron deficiency from poor diet, blood loss, and parasitic infections. Symptoms are often vague but include fatigue, weakness, and breathlessness. Treatment involves oral iron supplements which may cause side effects like dark stools but provide relief over 3-6 months of continued use.