Background: Probiotics are different types of friendly types of yeasts or bacteria that improve the health of humans as well as animals. Their formulation can be used to make a wide range of products, including foods, pharmaceuticals, nutritional supplements and animal feed. Numerous scientific studies have examined and demonstrated the benefits of probiotics for health. Since there may be concerns regarding the safety of probiotics, a thorough understanding of their advantages and disadvantages is crucial before they are widely used. The aim of this study is to shed light on the probiotic world, which has a long history of success across many different fields. Main Body: The definition of probiotics and related terminology, their usage, and the kinds of bacterial strains involved as different species of Lactobacillus; Bifidobacterium. etc., their mode of action and their applications for humans and animals were all covered in this study. Numerous advantages for human health were highlighted, including their ability to treat a range of gastrointestinal issues and their role in lowering the prevalence of numerous other illnesses and infections. Moreover, its possible source of antibiotic resistance, adverse metabolic activities, and other associated side effects such as sepsis were explained. Conclusions: Probiotics have non-neglected hazards that endanger human health and safety, despite their potential advantages and use in the treatment or prevention of numerous clinical disorders. More research on the dangers and proper usage of probiotics is advised because they are a double-edged currency that must be dealt with caution.