Booking Holdings

Priceline Group CEO Darren Huston touts his company's organic growth versus Expedia Inc.'s strategy of mostly acquiring companies that need to be put back on track. Rest assured, however, that Priceline would plunk down a few billion dollars on the right acquisition target. It just wasn't HomeAway, and TripAdvisor and Airbnb are too expensive.

While the big chains have tech and marketing people to optimize websites and their cost-per click campaigns, booking sites in transformation such as Booking.com, Trivago and TripAdvisor are squarely directed at making themselves more essential to smaller, independent hotels. It is another sign of the changing role of metasearch sites and online travel agencies in the mobile era.

TripAdvisor wanted to keep the details secret. But the price for finally getting the Priceline Group/Booking.com into TripAdvisor Instant Booking was playing the online travel agency exclusivity card. Expedia is shut out for now and can join later. Will Book on Google play a similar game?

Understanding how Priceline.com turns lurkers into customers is key to gauging its success.

As this TripAdvisor-Priceline Group partnership takes off, observe it closely because it signals a new stage in earnest in travel bookings -- the real emergence of third-party sites such as TripAdvisor and perhaps Google at some juncture that were primarily media sites as real forces in travel transactions.

Expedia's purchase of HomeAway sets the stage for big moves in the online booking sector.

Booking.com is telegraphing the fact that it is open to participate in Book on Google now that it agreed to participate in Book on TripAdvisor.

Booking.com wants to change the narrative: Its growth, and especially its girth, compare favorably with Airbnb's on the apartment rental front. And Booking.com can show some digital one-up-manship too because all of its 21 million rooms are instantly confirmable.

With the Priceline Group out of the running to get into the Expedia-HomeAway sweepstakes, it appears very likely that the deal will sail through toward closing.

TV advertising by online travel agencies has been very much in vogue over the last couple of years. But TripAdvisor decided it doesn't need it for now and instead is going to take its new partnership with Booking.com and run with that instead.