Abstract: Cancer is uncontrolled growth of cells that caused by DNA variations. Identifying the variations and their interactions in each cancer's genome will accelerate the understanding of the molecular basis of cancer. This work will improve our abilities of cancer prevention, early detection and treatment. So, American National Cancer Institute (NCI) and National Human Genome Research Institute (NHGRI) initiated. The Cancer Genome Atlas (TCGA) project. Unprecedented amount of data was generated in the process. We can learn more about the molecular basis of cancer by analyzing the data from TCGA, to lay the foundation for precision therapy and personalized cancer care. In this paper, we introduced the development of data, data types and levels, retrieval and application, and benefits of TCGA in detail. Our introductions aim to help researchers learn and use the dataset to develop more effective ways to diagnose, treat and prevent cancer.