Many real-world problems are solved using graphs. Networks are represented using graphs. Paths in a city, telephone network, or circuit network are examples of networks. Graphs are also utilized in social networking sites such as LinkedIn and Facebook. Graphs are a strong and adaptable data structure that allows you to easily express real-world connections between many types of data (nodes). A graph is made up of two major components (vertices and edges). The data is stored at the vertices (nodes), which are represented by the numbers in the picture on the left. The edges (connections) that link the nodes in the picture, i.e., the lines connecting the numbers.