It is possible, prior to flying or even arriving at the airport, to check yourself in to the flight. This has distinct advantages including

Getting to choose a preferred seat that is available
- Note: some airlines charge a fee for selecting premium seats in advance
Avoid the stress of checking in at the airport especially if running late
Avoiding the long queues at airport check-in, as there is normally a separate, “baggage-drop” queue to quickly handle the passengers who have already checked in on-line