I take a hard copy of bookings. I print it double sided to save clutter.

One thing I do keep on my phone is a pic of my luggage. It might help to know what they are looking for in a sea of black luggage on the carousel. My luggage is grey and orange.

The airline will have to pay to return you if you are deemed inadmissible at immigration, and onward travel is one of the requirements in some places. It can save them money to check, but after you've entered the country then it's no interest of theirs.

OP: Two printed copies of every booking on an itinerary. You never know when you'll lose one or when it might be kept by the check in agent or whoever.

Sure, the point is: Neither an airline can verify a ticket on a different carrier or the immigration officer with ease. Having a printout with some black ink on it doesn't say anything. They will always need to look to the eticket.

So, yes... it is good to have a e-ticket number for the return but having the itinerary printed out itself doesn't help (besides the ticket number printed on it)

Depends where I'm travelling to. US immigration, for example, frequently asks for return itinerary, and, in my experience, they much prefer you to just hand them a paper copy - so I print one out to make my life easier, after I've stumbled off a long-haul and waited for 90 minutes in a snaking queue.

Other countries, like India, although they have a very bureaucratic system of presenting flight documents (e.g. to enter the airport as well as at immigration, etc) are very comfortable with a soft copy, so I don't bother.

For simple trips, such as a domestic flight and a chain hotel, I don't bother. I have it on my phone if needed, and in case my phone dies it shouldn't be hard to obtain.

For international trips, or special situations like if I'm staying at a B&B or something, I will usually print it out to be safe.

If you are concerned about the environmental impacts, print on the back of used paper, or print 2 sheets to a page and double sided.

+1 to this also, few times had in Russian airport while flying domestic, the airport staff or police were asking the reservation or invoices of your stay, because hotel has to register you and they wont give any documents on this for you. So in these cases the reservation is basically only proof of registration.

Other cases also, if the immigration is asking those.

For the US, I always bring paper: I have found the US to be very bureaucratic and paper-orientated. Elsewhere, for modern countries I don't bother but I do take paper for countries with weak infrastructure.

Interesting, I (German citizen with ESTA) fly to the US (mostly BOS, EWR and SFO) at least once a month for the past years and NEVER had to show a return flight proof. They usually just ask how long I plan to stay and don't even listen to the answer as they are already stamping the passport.

I've been asked many many times for proof of return/onward flight at check in (and less frequently at immigration). Australia and New Zealand seem to be the worst for this. This usually happens when I have booked two one way flights as opposed to a return (so typically on mileage rewards). If you have booked a return then the airline knows you have a return so doesn't need to ask. In any case, always wise to have printouts for international travel.

From my research its a pass the buck issue. Airline that brings the passenger is responsible for removing said passenger should immigration deny entry. With a paid onward ticket the airline knows exactly who to point you to if passenger is denied entry.

I always bring paper and copies on international trips. I don't bother with paper for domestic though. I also keep PDF copies on at least 2 devices, usually a Kindle and my phone (or travel buddy's phone, work phone, etc.)

For international, I print hard copies of everything as I cannot rely on having cell coverage or internet service where I need it, such as in airports or at hotel check in desks.

Unfortunately many emailed hotel confirmations don't show all of the important information: room category/type, rate, cancellation policy, check in and check out times, special requests/guarantees, comments on the reservation, etc. You sometimes must print this at the time that you make the reservation. The "reminder" emails that hotels send out shortly before your arrival date are even worse as they tend to contain NO information other than the dates for your reservation--it's pointless except to remind you to cancel reservations that you won't be using, but frequently the email arrives just after your cancellation deadline.

In the US I rarely bother with paper printouts as the flights I take are short, and there's little to no risk of not being able to charge my phone. I always have paper printouts when travelling in India or China.

My work iPhone is a delicate and moody creature when the battery is pushed past 8 hours of use. With a sometimes 4 plus hour drive to the airport from the factory after working the mornings it's a 70/30 chance of the battery dying before I reach the airport. India airports require proof of travel to enter, and if the car I'm riding in doesn't have a USB charging port accessible I could be SOL.

Its not worth missing my flight out of India or China for the ease of not carrying 2 or 3 pages of paper for my flight itineraries.

I print flight itineraries for international. One common use is at airports that have a security checkpoint prior to the airline counters. The easiest thing to show them is paper.

Most places ask if you have a ticket out of the country, some ask for proof. An (always 'an' if there's a vowel after) itinerary can prove that