An electronic ticket, or e-ticket, is an electronic document, an agreement of air transportation between the passenger and the airline company. In fact, it is an electronic version of a usual paper ticket.
Therefore, the passenger may have only his/her ID (passport) to check in and board. The electronic ticket is already stored in the airline's database.
However, we recommend for the passenger to have a printed e-ticket/itinerary receipt (ITR) with the booking reference number, which will be sent to your email after payment for the flight ticket. The itinerary receipt (ITR) confirms that you bought the e-ticket. It can be required during check-in, passport and customs control; it will also help you not to forget the time of departure, arrival, or transfer.