The objective of the tool is to investigate the long-run impact of future demographic, key macroeconomic, and selected environmental trends on international travel demand over time. Specifically, the future demographic trends are population size and age structure of the population in departure countries. The simulation tool is meant to be easy and flexible to use. Simulation outcomes should however be interpreted with care. In case of doubt about the interpretation of simulation outcomes, do not hesitate to contact research experts or the authors of the tool. The simulation tool is provided “as-is”, without any warranty of any kind. Neither the authors of the tool nor their employer shall be held liable for any consequences from the usage of the simulation tool. The model is provided in two parts: the simulation tool, and the user manual on the simulation tool. Reading of the user manual before use of the simulation tool is recommended.