Anaerobic oxidation of methane (AOM) is a key microbial process that regulates global methane fluxes. This review summarizes current knowledge and gaps regarding AOM and its key catalysts, the ANME clades and their bacterial partners. Methane is the most abundant hydrocarbon in the atmosphere and a major greenhouse gas, contributing about 20% of postindustrial global warming. AOM is primarily carried out by anaerobic methanotrophic archaea (ANME), which use methane and sulfate as electron donors and acceptors, respectively, in the reaction CH₄ + SO₄²⁻ → HCO₃⁻ + HS⁻ + H₂O. ANME are closely related to methanogens and are found in various environments, including cold seep ecosystems, SMTZs, hydrothermal vents, and deep biosphere. AOM is often carried out in consortia with sulfate-reducing bacteria (SRB), which provide an electron sink. The ANME populations are divided into several clades, with ANME-1, ANME-2, and ANME-3 being the most well-studied. ANME-2 is the most common clade, found in a wide range of environments, while ANME-1 and ANME-3 are less common. The ANME populations are often associated with specific bacterial partners, such as Desulfosarcina and Desulfobulbus. AOM is limited to anoxic habitats and is influenced by the availability of methane and sulfate. The rates of AOM vary widely, from a few pmol cm⁻³ day⁻¹ in subsurface SMTZs to several μmol cm⁻³ day⁻¹ in surface sediments. AOM is also influenced by environmental factors such as pressure, salinity, temperature, and pH. The physiological characteristics of AOM consortia include a stoichiometric ratio of approximately 1:1 for methane and sulfate, and a low energy yield. The growth parameters of ANME are slow, with a doubling time of approximately 7 months. The functional genes, genomics, and proteomics of ANME have been studied, with the mcrA gene being a key marker for ANME. The mcrA gene is involved in the methyl-coenzyme M reductase (MCR) reaction, which is essential for AOM. The study of AOM has revealed important insights into the microbial processes that regulate global methane fluxes and the role of ANME in the carbon cycle.Anaerobic oxidation of methane (AOM) is a key microbial process that regulates global methane fluxes. This review summarizes current knowledge and gaps regarding AOM and its key catalysts, the ANME clades and their bacterial partners. Methane is the most abundant hydrocarbon in the atmosphere and a major greenhouse gas, contributing about 20% of postindustrial global warming. AOM is primarily carried out by anaerobic methanotrophic archaea (ANME), which use methane and sulfate as electron donors and acceptors, respectively, in the reaction CH₄ + SO₄²⁻ → HCO₃⁻ + HS⁻ + H₂O. ANME are closely related to methanogens and are found in various environments, including cold seep ecosystems, SMTZs, hydrothermal vents, and deep biosphere. AOM is often carried out in consortia with sulfate-reducing bacteria (SRB), which provide an electron sink. The ANME populations are divided into several clades, with ANME-1, ANME-2, and ANME-3 being the most well-studied. ANME-2 is the most common clade, found in a wide range of environments, while ANME-1 and ANME-3 are less common. The ANME populations are often associated with specific bacterial partners, such as Desulfosarcina and Desulfobulbus. AOM is limited to anoxic habitats and is influenced by the availability of methane and sulfate. The rates of AOM vary widely, from a few pmol cm⁻³ day⁻¹ in subsurface SMTZs to several μmol cm⁻³ day⁻¹ in surface sediments. AOM is also influenced by environmental factors such as pressure, salinity, temperature, and pH. The physiological characteristics of AOM consortia include a stoichiometric ratio of approximately 1:1 for methane and sulfate, and a low energy yield. The growth parameters of ANME are slow, with a doubling time of approximately 7 months. The functional genes, genomics, and proteomics of ANME have been studied, with the mcrA gene being a key marker for ANME. The mcrA gene is involved in the methyl-coenzyme M reductase (MCR) reaction, which is essential for AOM. The study of AOM has revealed important insights into the microbial processes that regulate global methane fluxes and the role of ANME in the carbon cycle.