Entering a country during a layover in 2026 depends on your nationality and the length of your stay. If you have a long layover (usually 6+ hours) and wish to leave the airport "airside" area, you must clear Immigration and Customs. For many travelers, this requires a Transit Visa or a standard Tourist Visa, though citizens of "Visa-Waiver" countries can often enter with just an eTA (Electronic Travel Authorization). In 2026, some hubs like Singapore Changi or Doha International offer "Free Transit Tours" that include a temporary entry permit. However, if you are on a "Direct International Transit" (staying in the terminal), you do not need to enter the country. Always check if you need to re-claim and re-check luggage, as this often forces you to enter the country legally, requiring the appropriate 2026 visa documentation.