Everything from who you have poked, what events you have or have not attended and when and where you have logged into your account is logged and saved. Head to /settings and click ‘ Download a copy of your Facebook data’ and you might be surprised to see just how much information is on file. The amount of personal data that social networking sites like Facebook, Google Plus and Twitter have harvested from their billions of users is shocking. Photograph: Kimihiro Hoshino/AFP/Getty Images 3.