@Dinah12, I don't know how "most" people give guests access, but one popular solution is to use a Smart Lock of some sort. Smart Locks allow you to give a key code or use smart phones (or both) so guests can use the lock without having to exchange keys. Not having physical keys also eliminates the worry of guests copying the keys for later use.
Some models even automatically work with AirBnB to set themselves up automatically when an AirBnB reservation is made.
There are a lot of different Smart Locks with different capabilities. Search for "Smart Locks" on this Discussion Room, or you can search for "AirBnB Smart Lock" on Google.