Readers with status with a full-service airline or certain credit cards are familiar with airport lounges. Those spaces are run by the airlines themselves or owned by third-party companies that cater to status-holding frequent flyers, passengers in premium classes (typically business and first class), and holders of specific memberships like LoungeKey or Priority Pass. Occasionally, one-time-use lounge passes can be purchased at entry or within an airline's app. For airlines, these spaces are part of their flagship experience. They are often part of the first impression for customers, so they invest a lot to create the most unique experience. These spaces may even include a sauna like the Hall L lounge in CDG or Finnair's Platinum Wing lounge in Helsinki.