Childhood mortality refers to the death of children under the age of five. It is often measured as the number of deaths per 1,000 live births in a given year. Factors contributing to childhood mortality include malnutrition, infectious diseases, and lack of access to healthcare. Efforts to reduce childhood mortality have focused on improving maternal health, increasing vaccination rates, and providing clean water and sanitation. Organizations like UNICEF and WHO work globally to implement programs aimed at decreasing these rates and ensuring that children have a better chance of survival and healthy development.