Aharon Oren reviews microbial life in high salt environments, highlighting the diversity and adaptations of halophiles across the three domains of life. Halophiles are found in Bacteria, Archaea, and Eukarya, with distinct phylogenetic and physiological characteristics. The most salt-requiring halophiles are in the Archaea class Halobacteria, while some Bacteria, like those in the Halobacteriales, Halomonadaceae, and Halanaerobiales, are also halophiles. Halophiles use two main strategies to adapt to high salt: accumulating KCl or organic solutes. The first strategy requires extensive adaptation of intracellular enzymes, while the second involves accumulating compatible solutes like glycine betaine, ectoine, and others. The Halobacteriaceae family is a notable example of halophiles using the high-salt-in strategy. However, the red extremely halophilic Salinibacter, a Bacteroidetes member, uses the same strategy as Halobacteriaceae, showing that halophiles can be found outside traditional halophile groups. The review also discusses the phylogenetic distribution of halophiles, their physiological adaptations, and the diversity of compatible solutes used by different halophiles. It emphasizes the need for reevaluation of previous classifications and the discovery of new halophilic organisms. The study highlights the complexity of halophilic microorganisms and their ability to adapt to extreme environments.Aharon Oren reviews microbial life in high salt environments, highlighting the diversity and adaptations of halophiles across the three domains of life. Halophiles are found in Bacteria, Archaea, and Eukarya, with distinct phylogenetic and physiological characteristics. The most salt-requiring halophiles are in the Archaea class Halobacteria, while some Bacteria, like those in the Halobacteriales, Halomonadaceae, and Halanaerobiales, are also halophiles. Halophiles use two main strategies to adapt to high salt: accumulating KCl or organic solutes. The first strategy requires extensive adaptation of intracellular enzymes, while the second involves accumulating compatible solutes like glycine betaine, ectoine, and others. The Halobacteriaceae family is a notable example of halophiles using the high-salt-in strategy. However, the red extremely halophilic Salinibacter, a Bacteroidetes member, uses the same strategy as Halobacteriaceae, showing that halophiles can be found outside traditional halophile groups. The review also discusses the phylogenetic distribution of halophiles, their physiological adaptations, and the diversity of compatible solutes used by different halophiles. It emphasizes the need for reevaluation of previous classifications and the discovery of new halophilic organisms. The study highlights the complexity of halophilic microorganisms and their ability to adapt to extreme environments.