How did travel or hotel booking websites like Ctrip, Qunar and Yilong develop hotel cooperation?

There are many distribution channels in the hotel, including online channels (Ctrip, E Long, Green Mango Travel Network, mango net, Tongcheng.com, Qunar, Taobao and other distribution platforms), travel agencies, private room companies, individual travelers and business travel companies. It is impossible for a hotel to maintain the backstage of so many websites at the same time, so it is generally recommended to choose about three websites as partners, and it is recommended not to cooperate with the hotel yourself. Price, inventory and room condition are difficult to guarantee.