This course is devoted to the biology behind cancer initiation and development. The course will discuss how normal cells become tumor cells, how tumor cells develop into tumors, and how tumors metastasize in the far distant tissue as well as the current strategy and prospective of cancer prevention and treatment. I expect that you will leave this course with a gain in the mechanistic understanding of human cancer and more importantly, an appreciation for the importance of the basic science that shapes the therapeutic strategy of human cancer.