Ants are crucial components of ecosystems, contributing significantly to biodiversity and ecosystem functioning. They are not only a major part of animal biomass but also act as ecosystem engineers, influencing soil processes and environmental conditions. Ant biodiversity is exceptionally high, yet it is highly sensitive to human impacts, which can reduce its richness. This review discusses ant biodiversity patterns, methods of quantification, and the effects of human activities such as land use change, pollution, invasions, and climate change on ant biodiversity. The role of ants in ecosystems is primarily examined through their impact on soil processes, emphasizing their role as ecosystem engineers. Ants are classified in the family Formicidae, within the order Hymenoptera, and have been evolving successfully since the Cretaceous. There are 16 subfamilies, 296 genera, and over 15,000 species of ants, with around 10,000 described. The number of undiscovered species is extremely high. Ant biodiversity varies geographically, with the Neotropical and African regions having the most endemic genera, while the Nearctic and Oriental regions have the least. Ants are found in a wide range of habitats, from the Arctic Circle to the Equator, but are absent from Iceland, Greenland, and Antarctica. Species diversity tends to decrease with increasing latitude, altitude, and aridity, although tropical areas and continental forests, despite being among the least studied, have the highest recorded species diversity. The review highlights the importance of ants in soil functioning, particularly their role as ecosystem engineers. It also identifies gaps in current knowledge about ant-soil interactions and suggests areas for further research. Ants are essential for maintaining ecosystem services, and understanding their biodiversity and ecological roles is crucial for effective conservation and management strategies.Ants are crucial components of ecosystems, contributing significantly to biodiversity and ecosystem functioning. They are not only a major part of animal biomass but also act as ecosystem engineers, influencing soil processes and environmental conditions. Ant biodiversity is exceptionally high, yet it is highly sensitive to human impacts, which can reduce its richness. This review discusses ant biodiversity patterns, methods of quantification, and the effects of human activities such as land use change, pollution, invasions, and climate change on ant biodiversity. The role of ants in ecosystems is primarily examined through their impact on soil processes, emphasizing their role as ecosystem engineers. Ants are classified in the family Formicidae, within the order Hymenoptera, and have been evolving successfully since the Cretaceous. There are 16 subfamilies, 296 genera, and over 15,000 species of ants, with around 10,000 described. The number of undiscovered species is extremely high. Ant biodiversity varies geographically, with the Neotropical and African regions having the most endemic genera, while the Nearctic and Oriental regions have the least. Ants are found in a wide range of habitats, from the Arctic Circle to the Equator, but are absent from Iceland, Greenland, and Antarctica. Species diversity tends to decrease with increasing latitude, altitude, and aridity, although tropical areas and continental forests, despite being among the least studied, have the highest recorded species diversity. The review highlights the importance of ants in soil functioning, particularly their role as ecosystem engineers. It also identifies gaps in current knowledge about ant-soil interactions and suggests areas for further research. Ants are essential for maintaining ecosystem services, and understanding their biodiversity and ecological roles is crucial for effective conservation and management strategies.