A flight search engine answers a well-defined question: which available flights connect two airports? A door-to-door travel planner must answer a more difficult one: which sequence of flights, trains, coaches, and ferries can plausibly connect two places, even if the destination has no airport? ...
Source: [Dev.to](https://dev.to/routavio/engineering-a-multimodal-travel-planner-on-a-228060-edge-graph-4i0d)