In the context of "world counting" or travel milestones, transiting typically does not count as visiting a country unless you pass through immigration and enter the "landside" of the airport. If you stay "airside" in the secure transit zone between two international flights, you have technically never legally entered the territory. From a visa perspective, however, 2026 rules vary: the U.S., Canada, and the UK often require a "Transit Visa" (like the C-1 or DATV) for certain nationalities even if you never leave the terminal. For the European Schengen Area, a "Direct Airside Transit Visa" is mandatory for some, while others are exempt. If you have a 12-hour layover and use a Transit Visa or an ETIAS to exit the airport, see a landmark, and have a meal, you have officially "visited" the country. For the purpose of a "countries visited" map, most travelers only count a stop where they have cleared customs and touched the soil outside the airport terminal.