The article provides a comprehensive review of the genetics, mechanism of action, and functional domains of Clostridium difficile toxins TcdA and TcdB. These toxins, encoded by a pathogenicity locus within the *C. difficile* chromosome, are glucosyltransferases that target and inactivate small GTPases (Rho, Rac, and Cdc42) via UDP-glucose-dependent glycosylation. The toxins enter host cells through receptor-mediated endocytosis, requiring an acidic environment for translocation and membrane translocation. They disrupt actin cytoskeleton organization, leading to cell rounding, blebbing, and eventually apoptosis. TcdA and TcdB play crucial roles in *C. difficile*-associated disease, including pseudomembranous colitis, by altering cell signaling pathways and increasing epithelial permeability. The toxins' impact on cell morphology and GTPase signaling pathways contributes to the disease's severity. The review also discusses the genetic organization of the pathogenicity locus, toxinotypes, and environmental signals regulating toxin expression. Despite the lack of genetic manipulation in *C. difficile*, studies using surrogate approaches have strongly implicated these toxins in disease, with monoclonal antibodies to TcdA providing protection in animal models. The article highlights the importance of understanding the molecular mechanisms of TcdA and TcdB in advancing the treatment and management of *C. difficile*-associated disease.The article provides a comprehensive review of the genetics, mechanism of action, and functional domains of Clostridium difficile toxins TcdA and TcdB. These toxins, encoded by a pathogenicity locus within the *C. difficile* chromosome, are glucosyltransferases that target and inactivate small GTPases (Rho, Rac, and Cdc42) via UDP-glucose-dependent glycosylation. The toxins enter host cells through receptor-mediated endocytosis, requiring an acidic environment for translocation and membrane translocation. They disrupt actin cytoskeleton organization, leading to cell rounding, blebbing, and eventually apoptosis. TcdA and TcdB play crucial roles in *C. difficile*-associated disease, including pseudomembranous colitis, by altering cell signaling pathways and increasing epithelial permeability. The toxins' impact on cell morphology and GTPase signaling pathways contributes to the disease's severity. The review also discusses the genetic organization of the pathogenicity locus, toxinotypes, and environmental signals regulating toxin expression. Despite the lack of genetic manipulation in *C. difficile*, studies using surrogate approaches have strongly implicated these toxins in disease, with monoclonal antibodies to TcdA providing protection in animal models. The article highlights the importance of understanding the molecular mechanisms of TcdA and TcdB in advancing the treatment and management of *C. difficile*-associated disease.