Push-button start is standard on most modern cars, trucks and SUVs today. How does it work and is it better than ignition keys?

If your car's smart key dies on you, it's still possible to unlock your car and start the ignition without replacing the key's battery immediately.

How do you start your car? Is it a push button with a proximity key, a standard key that you turn, or that weird thing BMW did for a while where you have to put the fob in the dash before the button ...