This what you choose as your "User Name" when you sign up for our service and the password you set. We don't save your password in plain text, but we do know your password. This is "address" of your computer or other devices (like a phone or iPad) that you use to access the Internet. Generally speaking, your IP address is unique at the moment when you access our website, so it can be used to track you down. For more information, please check https://en.wikipedia.org/wiki/IP_address . We will know about your email address if you share with us. This is also an unique piece of information about you and can be used to identify you. When you take a challenge on our website, we will record all the exercises you take with your answers. When you visit this website, we will record the time when you sign in and the time when you leave. Your nick name is your identifier when you use our service. We use your user name and password to authenticate you when you log in to our service. We also use your user name to uniquely track your activity on our website. We don't use your IP address to track you but we will use that information for auditing your activity when you are not signed in to our system. Also our service providers, like the website hosting provide and cloud computation providers also know your IP address without us sharing with them. If you share you Email address with us, we will use it to send you updates about our service, like the maintainence schedule or upgrades. We will also send special challenges and tournament information to you through your email. We use the exercises you have taken to track your progress and evaluate your skill level. We use your performance when your solve the exercises to identify your strong and weak areas and prepare more customized exercises for you. We use the time you spent on our website to check how "hard" you are working and use it as one of the factors to decide the rewards you will get.