This lecture covers the theory behind cruising with an aircraft. It starts off with talking about the different aspects of flight affecting cruise strategy, followed by finding an analytic solution to the range and aircraft can cover. Next an example is brought about the global flyer, which can fly around the entire world in one cruise. As the weight breakdown of an aircraft greatly affects the performance of an aircraft during cruise, this subject is expanded on, followed by the economics behind the whole. Finally this lecture is summarized.