Jump onto Expedia or Priceline to search for a flight, and you’ll likely see an “opaque” fare: a price with no carrier or even the exact time. How does this help, one might ask. Well, it’s not meant to help you; it’s meant to help the airlines. These mysterious fares are a tool that can help carriers move seats they have a hard time selling. This strategy is now turning even more complex with “secret fares,” the next evolution in the airline quest to more tightly control ticketing inventory and the costs imposed by companies that distribute their fares. It even involves an app. Wednesday, the mobile-only travel seller Hopper began offering these “secret fares” from a half-dozen airlines at prices that could be as much as 35% below what the same carriers publish elsewhere. The initial 60,000 routes covered will be international and mostly long-haul. <br/>