Graph theory is a branch of mathematics focused on the study of graphs, which are structures made up of nodes (vertices) connected by edges (links). In cybersecurity, graph theory is used to model and analyze networks, such as computer systems, social networks, or the internet. By representing entities as nodes and their relationships as edges, cybersecurity professionals can detect vulnerabilities, track threats, and optimize network defenses. Applications include identifying attack paths, mapping malware spread, and visualizing complex relationships within large-scale infrastructures. Graph theory enables a deeper understanding of connectivity and interdependencies, which is crucial for effective network security and threat mitigation.