The article reviews the lung microbiome, highlighting its history, composition, and functions. Initially believed to be sterile, the lung microbiome has been discovered to consist of bacteria, fungi, and viruses, with a unique mobility due to the respiratory system's clearance mechanisms. The lung microbiome is transient and mobile, differing from other organs' microbiomes. Recent studies have focused on the pulmonary bacteriome, mycobiome, and virome, emphasizing their roles in innate and adaptive immune responses. The lung microbiome is closely linked to the oropharyngeal and gut microbiomes, particularly through the gut-lung axis, which influences metabolism, immunity, and disease progression. The article discusses the impact of the lung microbiome on various respiratory diseases, including asthma, COPD, fibrosis, bronchiectasis, and pneumonia, as well as its role in COVID-19 and lung cancer. It also explores the therapeutic potential of the lung microbiome in treating these diseases and identifies areas for future research.The article reviews the lung microbiome, highlighting its history, composition, and functions. Initially believed to be sterile, the lung microbiome has been discovered to consist of bacteria, fungi, and viruses, with a unique mobility due to the respiratory system's clearance mechanisms. The lung microbiome is transient and mobile, differing from other organs' microbiomes. Recent studies have focused on the pulmonary bacteriome, mycobiome, and virome, emphasizing their roles in innate and adaptive immune responses. The lung microbiome is closely linked to the oropharyngeal and gut microbiomes, particularly through the gut-lung axis, which influences metabolism, immunity, and disease progression. The article discusses the impact of the lung microbiome on various respiratory diseases, including asthma, COPD, fibrosis, bronchiectasis, and pneumonia, as well as its role in COVID-19 and lung cancer. It also explores the therapeutic potential of the lung microbiome in treating these diseases and identifies areas for future research.