Booking.com is the dominant player in Europe with something approaching 50% of all online hotel bookings going through them. They are unique in that they have t

Booking.com is the dominant player in Europe with something approaching 50% of all online hotel bookings going through them. They are unique in that they have tens of thousands of small hotels that use them exclusively as their booking engine and don't distribute to other online travel agencies. Booking.com uses an agency model so the hotels pay them a commission that tends to be lower than the margin they share with Expedia and others on the merchant model. However, since Booking.com has so much leverage in the marketplace, they have started charging more for premium placement, etc. that hotels have to comply with if they want exposure to their massive audience.