When you add a task, the text you entered is saved to your browser's local storage and can only be deleted by hitting the "X" button on the task item you created. This allows you to close the app and reopen it at any time in the future and still have your tasks! If you completed an item, you can hit the checkmark to add it back into the "To Do" area. If you are in a Privacy mode, or have Javascript disabled, the app will sadly never remember what you added. Enjoy!