1. Passport- first and most obvious is your passport- especially if you are traveling internationally; you will not be able to leave the country without it- and it is also a good form of identification even in cases when it is not absolutely necessary. For example, I went to Florida for spring break a few years ago and used my Canadian passport to get into bars because they could not understand the French on my Quebec driver’s license.
2. Travel tickets, or paper printout of your e-ticket would be the second thing to absolutely make sure that you have. While many airlines are issuing e-tickets in favour of the paper variety, it’s better to be safe and you can end up in an awkward situation with airport staff if you do not have paper proof. Â As I consider myself to be an experienced traveler last year I stopped taking my own advice and was passing through Heathrow airport when, while transferring between terminals, I was asked for a copy of my airline ticket by airport security to be stamped. I had a confirmed e-ticket on my next flight but I did not have any paper copy. So, I sheepishly held up my cell phone to show them the confirmation number and was asked to step out of the line and wait for the supervisor to arrive. It worked out in the end but the inconvenience of the incident reminded me to bring a printout.
3. Copies of hotel and car rental reservations- On more then a couple of occasions I have arrived at a hotel or a car rental desk and the agent cannot find any evidence of my reservation until I show them a printout (especially if the reservation was made through a travel website such as expedia.com or travelocity.com.
If you are traveling to a new country may be risky for any reason I would add one last item: keep a note with the address and phone number of your nearest embassy/consulate in a safe place- this can save you a lot of hassle if your documents are lost or stolen.