The document discusses the concept of essential medicines and rational use of medicines. It defines essential medicines as those that satisfy the priority healthcare needs of the population based on criteria such as public health relevance, efficacy, safety and cost-effectiveness. Rational use requires patients receive appropriate medications for an adequate time at lowest cost. Irrational use can lead to ineffective and unsafe treatment, increased morbidity and mortality, and unnecessary costs. Strategies to promote rational use include education and training of healthcare providers, use of treatment guidelines, and ensuring availability of essential medicines.