This book gives an insight to the applications of graph theory in various fields including chemistry. The most significant tool of chemical graph theory is topological index that is used to gather data about a chemical compound and subsequent studies of quantitative structure-activity relationships/quantitative structure-property relationships (QSAR/QSPRs) analysis. The data obtained by topological indices are extensively used by chemists in drug design. It highlights about the various tools like graph operator, transformations and bounds related to chemical graph theory.