You start with a world map showing which countries are connected to which other countries. A small tutorial shows what this map can do.
The color shows how many flight routes there are between the two countries.
Upon clicking on the "Graph" button, the image transforms into a graph, showing the currently active country (or Belgium if no country was selected) and all the countries it's connected to. When you click any of the countries, they are expanded, and all countries they are connected to are shown. Hovering over a country shows all connections between the central country and the country being hovered.