Graph theory is the study of points and lines, and concepts like vertices and edges. It has many applications, including map coloring, Google Maps, and football games. Graph theory can be used to color maps with the minimum number of colors without any adjacent regions sharing the same color. It is also used in Google Maps for functions like estimating travel times and showing traffic conditions. In football, a match can be represented as a network with players as vertices and passes as edges, allowing analysis of things like which team has a more balanced network.