With a loyalty program that will soon reach 100 million guests, Hilton Worldwide is doubling down on its message to customers, asking them to skip the middleman and book their stays directly with hotels.

Online travel agencies (OTAs) like Expedia and Hotels.com make up a sizable portion of the booking industry, and often have more consumer data from the transactions than the hotels themselves.

Loyalty programs like Hilton Honors have a treasure trove of information beyond a customer’s name, address and credit card. The data gathered during booking, like demographics and spending habits, allows Hilton to get to know customers’ personal preferences, like whether they need a hypoallergenic pillow, and target them with promotional material for future trips.

Related: Hilton targeting younger travelers for its direct booking strategy