Fermented foods represent a cornerstone of global culinary traditions, underpinned by intricate microbial communities that drive flavor development and preservation. This chapter examines the microbial ecology and functional interactions across representative staple and traditional fermented foods, including fermented vegetables (sauerkraut, kimchi), fermented condiments (soy sauce, vinegar, miso, doubanjiang), and fermented alcoholic beverages (Chinese baijiu, wine, sake, Huangjiu). Recent meta-omics advances have revealed dynamic community succession, cross-feeding networks, quorum-sensing mechanisms, and key microorganisms contributing to flavor metabolites and health-promoting compounds. Furthermore, synthetic microbial communities and starter engineering are discussed as strategies to standardize fermentation, enhance quality, and develop novel functional products.