Peter,
Thank you for reaching out. There may be different guidelines in different states. I can tell you in Colorado it is an endorsement that you apply to your policy. It is called the Home Host Advantage and it costs $50/year to carry the additional insurance. Basically how this works is it changes the definition of "Business" in the guidelines to extend to short-term rentals, such as Airbnb.
It is going help cover your personal property for things such as a renter stains your sofa, area rug, etc. If they break your glasses or china. There are a lot of other coverages that I am happy to send in a message.
If you do have any other questions, feel free to reach out to me!
Have a great weekend,
Tiffany