In the old days (when I used to travel) a ticket was a piece of paper. It had some substance. Now there is a multitude of names (and perhaps there was before as well although I feel more uncertain now).
Emirates Airlines offer an “e-Ticket Receipt & Itinerary” A local carrier, Bangkok Air, gives me a “eTicket Receipt”, and Brussels airlines “e-ticket travel itinerary”. On Ryanair you get a booking reference only via email and later the (possibility to write a) boarding pass.
On a new airline, there is always a moment of uncertainty for me. Did I only get a documentation of a financial transaction in connection with me buying a ticket, or was it the ticket itself?
I realize that there are a multitude of other issues and reasons why you might not be allowed to board (passport or perhaps visa issues, health concerns etc.) so the ticket doesn't solve everything, but I still wonder if there is (or should be) an international (IATA?) standard for this document which essentially guarantees your trip and used to be a “ticket” and nothing else?