Childhood pneumonia is the leading cause of mortality in children under five years of age, with an estimated 156 million new episodes annually worldwide, of which 151 million occur in developing countries. The majority of cases are concentrated in India, China, Pakistan, Bangladesh, Indonesia, and Nigeria. Approximately 7–13% of these cases are severe enough to require hospitalization. Key risk factors include lack of exclusive breastfeeding, undernutrition, indoor air pollution, low birth weight, crowding, and lack of measles immunization. Pneumonia accounts for about 19% of all child deaths under five, with over 70% occurring in sub-Saharan Africa and Southeast Asia. The main pathogens associated with childhood pneumonia are Streptococcus pneumoniae, Haemophilus influenzae, and respiratory syncytial virus. The incidence of clinical pneumonia in children under five is estimated at 0.29 episodes per child-year in developing countries and 0.05 in developed countries. The highest incidence is found in South-East Asia, followed by Africa and the Eastern Mediterranean. The study highlights the need for accurate data on the distribution of pneumonia cases and the importance of addressing risk factors to reduce mortality. The main bacterial causes of pneumonia in developing countries are Streptococcus pneumoniae and Haemophilus influenzae, while respiratory syncytial virus is the leading viral cause. Vaccines against these pathogens, such as the Hib and pneumococcal vaccines, are effective in preventing pneumonia. Future research and new vaccines targeting a broader range of pathogens are needed to further reduce the burden of pneumonia in children.Childhood pneumonia is the leading cause of mortality in children under five years of age, with an estimated 156 million new episodes annually worldwide, of which 151 million occur in developing countries. The majority of cases are concentrated in India, China, Pakistan, Bangladesh, Indonesia, and Nigeria. Approximately 7–13% of these cases are severe enough to require hospitalization. Key risk factors include lack of exclusive breastfeeding, undernutrition, indoor air pollution, low birth weight, crowding, and lack of measles immunization. Pneumonia accounts for about 19% of all child deaths under five, with over 70% occurring in sub-Saharan Africa and Southeast Asia. The main pathogens associated with childhood pneumonia are Streptococcus pneumoniae, Haemophilus influenzae, and respiratory syncytial virus. The incidence of clinical pneumonia in children under five is estimated at 0.29 episodes per child-year in developing countries and 0.05 in developed countries. The highest incidence is found in South-East Asia, followed by Africa and the Eastern Mediterranean. The study highlights the need for accurate data on the distribution of pneumonia cases and the importance of addressing risk factors to reduce mortality. The main bacterial causes of pneumonia in developing countries are Streptococcus pneumoniae and Haemophilus influenzae, while respiratory syncytial virus is the leading viral cause. Vaccines against these pathogens, such as the Hib and pneumococcal vaccines, are effective in preventing pneumonia. Future research and new vaccines targeting a broader range of pathogens are needed to further reduce the burden of pneumonia in children.