Some data is technically necessary to be able to visit the page at all. A so-called cookie stores identifiers that make it possible to respond to your individual requests. It contains a session ID - a unique, anonymous user ID combined with an authentication identifier (user_data). A security identifier (csrf) is also stored to prevent a particular type of online attack. All of these fields are alpha-numeric, with almost no relation to your real identity. The only exception is that we monitor some requests with the IP address that you are currently using, so that we are able to detect malicious use or system defects. Additionally, a technical field is stored (singletab) to ensure that some interactions are only processed in the browser tab that is currently active. For example, a new chess game will not be opened in all your current tabs. We use your local storage to save the difference between your local clock and our server time (serverUserTimeOffset), so that we are able to display the date and time of events correctly for you. We measure how our page is used with Google Analytics so that we can decide which features to implement next and how to optimize our user experience. Google stores your device identifiers and we send tracking events (such as page requests) to Google Analytics. These have no direct relationship to your person except for the IP address currently being used and your Google Analytics identifiers. You can also enable more data fields, as described in the other sections. Your personal decision on which data storage to enable is also stored as necessary information (consent).