The article discusses the multifaceted roles of macrophages in development and disease. Macrophages, which are found in primitive multicellular organisms, play crucial roles in tissue development, including branching morphogenesis, neuronal patterning, angiogenesis, bone morphogenesis, and adipose tissue generation. Depletion of macrophages impairs tissue formation and function. In diseases such as cancer, the unrestrained acquisition of these developmental macrophage functions exacerbates pathology by enhancing tumor progression, metastasis, and angiogenesis. The review highlights the importance of macrophages in various developmental processes and how these functions can be subverted in pathological conditions. It also reviews the classification of macrophages, their differentiation, and the factors involved in their development. Additionally, the article explores the trophic functions of macrophages in bone morphogenesis, ductal branching, neural networking, and angiogenesis. Finally, it discusses the role of macrophages in diseases such as cancer, rheumatoid arthritis, and lipid metabolism disorders, emphasizing how their developmental functions can contribute to disease pathology.The article discusses the multifaceted roles of macrophages in development and disease. Macrophages, which are found in primitive multicellular organisms, play crucial roles in tissue development, including branching morphogenesis, neuronal patterning, angiogenesis, bone morphogenesis, and adipose tissue generation. Depletion of macrophages impairs tissue formation and function. In diseases such as cancer, the unrestrained acquisition of these developmental macrophage functions exacerbates pathology by enhancing tumor progression, metastasis, and angiogenesis. The review highlights the importance of macrophages in various developmental processes and how these functions can be subverted in pathological conditions. It also reviews the classification of macrophages, their differentiation, and the factors involved in their development. Additionally, the article explores the trophic functions of macrophages in bone morphogenesis, ductal branching, neural networking, and angiogenesis. Finally, it discusses the role of macrophages in diseases such as cancer, rheumatoid arthritis, and lipid metabolism disorders, emphasizing how their developmental functions can contribute to disease pathology.