This course will discuss the composition and function of the unique microbial communities harbored in the gastrointestinal, respiratory, and urogenital tracts, oral cavity, and skin. Lifestyle factors that alter the healthy balance within each of these communities will be described. Therapeutic modalities to restore microbial balance will be considered with emphasis on restoring homeostasis and health. This course is designed to provide a basic understanding and appreciation for these unique communities and their profound contribution.