You should take a copy of all your confirmation emails from airlines, hotels, car rental firms, etc., and not just the confirmation number. When traveling internationally, it’s always better to have the complete confirmation to avoid confusion. This is especially important if you booked through a third party and not directly with the airline or hotel. Some foreign airlines require you to have your e-ticket receipt. You may also need it to prove to immigration in the country you are visiting that you have an outward bound ticket.
IAH TIP: You should register your destination and trip plans with the US Department of State before you leave the country. In case of a national emergency or problem in the country you are visiting, the local embassy will know where you are.
Make sure to leave a copy of your itinerary with a friend or relative. In case of emergency it will make it easier for them to contact you. An easy way to manage your itineraries is to use tripit.com. You can build your itinerary piece by piece as you make reservations and when you’re done, you can automatically post it on the web, share it with others via email or PDF and more.
IAH TIP: In addition to taking paper copies of our confirmations, we also upload encrypted copies to a secure website as a backup.
You now need a passport to travel anywhere internationally. If you don’t have a passport, make sure you start the application process in plenty of time to get your passport before your departure. The late spring and summer season have the longest wait times. US citizens can find out more about applying for a passport on the 

