Network theory is a branch of applied mathematics and computer science that focuses on the study of complex systems composed of interconnected nodes or entities. These networks can take many forms, such as social networks, communication networks, biological networks, or transportation networks. The main goal of network theory is to understand the structure, dynamics, and behavior of networked systems, including how information, resources, or influence flow through these networks. Researchers in this field use mathematical models and algorithms to analyze and predict the behavior of networks, identify patterns and structures within them, and optimize their performance. Network theory has applications in a wide range of disciplines, including sociology, physics, biology, computer science, and engineering. It is used to study phenomena such as the spread of diseases, the formation of social networks, the functionality of the internet, and the structure of biochemical pathways. By studying networks, researchers can gain insights into the complex interactions and relationships that underlie many natural and artificial systems.