The most crucial genetic interpretation that lies behind many natural surrounding molecular phenomena was presented in this conceptual textbook in an illustrated - easy way. The contents of this book have distributed on eleven chapters, which contains more than two hundred fifty figures drawn by author's fingers himself. The chemical structure of nucleic acids, the way of their packaging, the gene flow essential data that formed as a result of the specialized arrangement of these nucleotides was discussed. Then, the modes of genes replication, transcription, translation, and the control of their expression, were explained as well. Moreover, the means by which the genetic material can be transferred among bacterial cells in nature was clarified and made as an introduction to identifying the scientific basis that human beings based on in their direct intervening in gene transfer from one organism to the other counterpart. Hence, it's considered as a basis of gene cloning experiments. Eventually, the most common tools used in dealing with genes are reviewed to pave the way for a vast imagination for the readers to the known practical applications of this tiny interesting world.