So many times I hear this classic “I didn’t know I needed a Visa”.
Here is the truth, you ALWAYS need a Visa.
“What?” You ask. Because in London they stamped your book and you were free to go as a US citizen. This is totally true, but that stamp, at customs and border, was your visa. No pre-registration and paperwork needed. Just the stamp.
Here is the thing though, sometimes the stamp doesn’t happen. And a big reason is that your passport may not have at least 6 months left on it for you to enter a specific country. Or more depending on where you are headed. In fact, many airlines won’t even let you board the plane if your passport is low on time. Meaning that week in Paris may be thrown away if you’re not prepared. This happens a lot.
Now for countries where you need advance permission, it’s vital to learn who needs what and what is needed. Meaning: countries like China may take longer and need you to buy plane tickets before you travel. Vietnam only takes a few days to process. Some countries only need a form when you land and a $50 fee. Just make sure you find out and find out at least a month or more in advance so you have time to plan.
Where do you find these details? Embassy websites and through the US state department’s website on travel: https://travel.state.gov/content/travel/en/international-travel/International-Travel-Country-Information-Pages.html
Don’t forget to also check warnings on places you are traveling to. https://travel.state.gov/content/travel/en/traveladvisories/traveladvisories.html/
Even consider registering with the state department in case you go missing. https://step.state.gov/step/
Other needs? Check with a travel agent or specialist that can at least point you in the right direction. Read a travel guide on your preferred country and ask around to others that have been to such locations.
Most of all, plan ahead, and have fun!