Instead of the usual song and dance about how privacy is important to companies in the business of selling our data, Yahoo CEO Marissa Mayer gave a refreshingly honest take today at the World Economic Forum on how privacy actually works. After saying the requisite user-privacy-is-important stuff, Mayer told Bloomberg Television's Erik Schatzker that people have to give up privacy in exchange for services: "I also think that privacy is always a trade-off. Because when you give up some of your information you get some functionality in return," she said. Yup, that's how it works. Often times when people get all hissy about Internet companies abusing their privacy, they forget that these optional, free services don't have much of an obligation to protect us. They do it to appease us and keep us around. But, when they do ask for privacy, it's in exchange for our use of their services. If we don't like it, we can leave. Watch Mayer's full interview at Davos below: