People checking in to their flight online do not have to print their boarding pass. Most airlines provide the option of printing a boarding pass from a home computer or at the airport kiosk.
Checking in online is convenient as it helps prevent standing in a long line at the airport. Even if a passenger doesn’t print the boarding pass after checking in, she can still avoid long lines by using a kiosk to check in. Some airlines email boarding passes to a mobile device. This email contains a boarding pass bar code that the passenger can show at the security checkpoint to gain entry.