I was trying to understand the model on which Airbnb operates and one thing I can't understand is that whenever a host signs up and put his listing he is automatically enrolled in Airbnb's Host Protection Insurance which provides primary coverage for Airbnb hosts and landlords up to $1 million USD for free of to the landlord? I was trying to understand the math behind it -

1) Is it an agreement with an insurance provider which Airbnb might have contracted with?

2) What type of insurance companies does provide such coverage?

3) Is there a specific term/type of insurance that the insurance industry uses for such agreement with companies like Airbnb?

4) Lastly, is it an out of pocket expense for Airbnb which it tries to recover from is revenues as they are not charging it from the landlords or its been charged to the renter?

Would really love some insight!

Thank you