This review summarizes recent literature on microorganisms with claimed probiotic properties. Probiotics are defined as live microorganisms that confer health benefits when administered in adequate amounts. Common probiotic genera include Lactobacillus, Bifidobacterium, Saccharomyces, Enterococcus, Streptococcus, Pediococcus, Leuconostoc, Bacillus, and Escherichia coli. The human microbiota is increasingly recognized for its role in health, and probiotics are considered a potential tool for correcting dysbiosis. However, the credibility of health claims and safety of probiotics must be established through science-based clinical studies. Probiotic properties are strain-specific, and accurate identification of strains is crucial. While many probiotics are generally safe for healthy individuals, caution is needed when using them in immunocompromised patients or those with leaky gut, as they can cause infections, sepsis, and fungemia. The review highlights the importance of strain-specific research and the need for rigorous clinical trials to evaluate the risk-benefit ratio of probiotics. It also discusses the health benefits of various probiotic strains, including their roles in preventing and treating conditions such as diarrhea, constipation, and inflammatory bowel disease. The review emphasizes the need for further research to establish the mechanisms of action and safety of probiotics, as well as the importance of accurate strain identification to ensure their safe and effective use.This review summarizes recent literature on microorganisms with claimed probiotic properties. Probiotics are defined as live microorganisms that confer health benefits when administered in adequate amounts. Common probiotic genera include Lactobacillus, Bifidobacterium, Saccharomyces, Enterococcus, Streptococcus, Pediococcus, Leuconostoc, Bacillus, and Escherichia coli. The human microbiota is increasingly recognized for its role in health, and probiotics are considered a potential tool for correcting dysbiosis. However, the credibility of health claims and safety of probiotics must be established through science-based clinical studies. Probiotic properties are strain-specific, and accurate identification of strains is crucial. While many probiotics are generally safe for healthy individuals, caution is needed when using them in immunocompromised patients or those with leaky gut, as they can cause infections, sepsis, and fungemia. The review highlights the importance of strain-specific research and the need for rigorous clinical trials to evaluate the risk-benefit ratio of probiotics. It also discusses the health benefits of various probiotic strains, including their roles in preventing and treating conditions such as diarrhea, constipation, and inflammatory bowel disease. The review emphasizes the need for further research to establish the mechanisms of action and safety of probiotics, as well as the importance of accurate strain identification to ensure their safe and effective use.