The journal publishes multidisciplinary research on microbiomes and microbiota in humans and animals, focusing on microbial community structure, function, interactions, and host communication. Key areas include microbial ecology and evolution, microbe–microbe and host–microbiome interactions, viromes/phageomes, mycobiomes, microbial dark matter, culturomics, gnotobiotic and synthetic communities, microbiome genomics, metatranscriptomics, metabolomics and proteomics, probiotics and postbiotics, diet–microbiome interactions, microbial metabolites, microbiota modulation, and microbiome-based therapies. Studies elucidating molecular mechanisms underlying microbiome function, health, and disease are particularly welcome.