Graph theory is a branch of mathematics that deals with the study of graphs, which are mathematical structures used to model relationships between objects. A graph consists of a set of vertices or nodes, connected by edges or links. Graph theory has applications in many different fields, including computer science, electrical engineering, biology, and social sciences. Researchers in graph theory study various properties of graphs, such as connectivity, coloring, and flows, in order to better understand the structure and behavior of complex systems.