In the previous chapters, we saw examples of how to model various types of systems by taking examples of subsystems of a travel booking application. Taking a relatively straightforward graph problem, we expanded the problem statement and plotted more information on the graph. We explored the details of how to model certain systems and discussed design decisions. While we have covered a wide variety of designs decisions that can be adopted for different scenarios, the examples covered are by no means exhaustive. For example, we can enhance the user experience by adding location-based features for the travelers, and we can build more information into the Bookings subgraph by allowing for sequencing among the journeys of a booking.