Oral streptococci are primary colonizers of the oral cavity, playing a dual role in health and disease. They maintain oral health by shaping the microbiota, modulating the immune system, and antagonizing pathogens. However, when they disseminate into the bloodstream, they can cause systemic diseases like infective endocarditis and hemorrhagic stroke. This review discusses the taxonomic diversity, roles, and contributions of oral streptococci to oral health and disease, focusing on their interactions with the host. Streptococci are classified into groups based on hemolytic potential and phylogenetic relationships. They are found in various oral niches and contribute to the formation of biofilms. Mutans streptococci, such as S. mutans, are major cariogenic agents. Oral streptococci also play a role in periodontal diseases by modulating the immune response and interacting with other bacteria. They can act as accessory pathogens, facilitating the colonization of pathogenic species. Streptococci exert immunomodulatory effects by suppressing inflammatory responses and inducing antimicrobial peptides. They also use adhesion molecules and virulence factors to colonize the oral cavity and interact with the host. Their ability to evade immune responses and form biofilms contributes to their pathogenic potential. The review highlights the complex interactions between oral streptococci and the host, emphasizing their role in maintaining oral health and preventing disease. Future research should focus on understanding these interactions and developing strategies to harness the beneficial properties of oral streptococci while mitigating their potential to cause disease.Oral streptococci are primary colonizers of the oral cavity, playing a dual role in health and disease. They maintain oral health by shaping the microbiota, modulating the immune system, and antagonizing pathogens. However, when they disseminate into the bloodstream, they can cause systemic diseases like infective endocarditis and hemorrhagic stroke. This review discusses the taxonomic diversity, roles, and contributions of oral streptococci to oral health and disease, focusing on their interactions with the host. Streptococci are classified into groups based on hemolytic potential and phylogenetic relationships. They are found in various oral niches and contribute to the formation of biofilms. Mutans streptococci, such as S. mutans, are major cariogenic agents. Oral streptococci also play a role in periodontal diseases by modulating the immune response and interacting with other bacteria. They can act as accessory pathogens, facilitating the colonization of pathogenic species. Streptococci exert immunomodulatory effects by suppressing inflammatory responses and inducing antimicrobial peptides. They also use adhesion molecules and virulence factors to colonize the oral cavity and interact with the host. Their ability to evade immune responses and form biofilms contributes to their pathogenic potential. The review highlights the complex interactions between oral streptococci and the host, emphasizing their role in maintaining oral health and preventing disease. Future research should focus on understanding these interactions and developing strategies to harness the beneficial properties of oral streptococci while mitigating their potential to cause disease.