> Some 58 percent of all offers on Airbnb in Germany are entire apartments or even apartment blocks - meaning professional landlords are effectively the core of Airbnb's business.

Someone working a full time job, who owns a primary residence as well as a secondary one for vacation. Does renting that secondary location means they are "a professional landlord" ? If someone who owns an apartment but is going abroad for a bit for vacation/work and have a family member take care of renting the place on AirBnB, are they "professional landlords" ?

I would assume professional landlord = landlord whose full time job is to take care of the rentals, I don't understand the jump from "this listing is an entire apartment" => "This is a professional landlord"