Candidiasis is an opportunistic infection caused by yeasts of the genus Candida. It represents about 80% of fungal infections. In recent years, there has been a great deal of interest in Candida infections because of the resurgence of diseases that weaken the immune system and the widespread use of immunosuppressive chemotherapy. A combination of factors related to the host's immunological and physiological status and the yeast itself favor Candida infections. Depending on the site of infection, candidiasis can be superficial or systemic. For better patient management, the choice of the method of diagnosis and identification of the Candida species responsible for the infection is essential because the infectious mechanisms and the sensitivity to antifungal agents can vary from one species of Candida to the other. This book provides an overview of the Candida species involved in human candidiasis, theirs virulence factors, the host defense mechanisms, the clinical aspects of candidiasis, the diagnostic methods, and some treatments available.