At what age is a child no longer a baby?

Stemming off a topic about "baby on board" stickers, what age is a child no longer a baby?

I obviously don't mean "my child will always be my baby" because I totally get that. I mean, when do you stop considering them babies?

Do you think there's an age when you should take those stickers off your car? Does it depend on whether or not the child is still in a carseat?

Note:

Those stickers (as far as I am aware) are intended for paramedics to know to look for and treat a baby first in an emergency. If that's incorrect, please let me know.