Graph theory is a branch of mathematics that studies the relationships between objects. It uses graphs, which are made up of vertices (or nodes) connected by edges (or lines). For example, a social network can be represented as a graph where people are vertices and friendships are edges. This helps us understand how different elements are connected and interact with each other. In addition to social networks, graph theory has applications in various fields like computer science, biology, and transportation. For instance, algorithms that find the shortest path in a network rely on graph theory principles. This makes it a powerful tool for solving real-world problems.