The "Attempted, but Incorrect" (or [a&i]) feature allows teachers to set a negative point value for questions that are answered, but have the wrong answer selected. This is typically used to punish guessing (questions left blank do not result in a penalty in this case), although it could be used as a "yay for trying!" partial credit (with a positive point value) if desired.
This is sometimes used in standardized tests, so including this a&i feature allows the teachers to more accurately recreate these standardized tests for practice purposes or to more accurately represent the scoring formulas used for a specific testing situation. (If you are not familiar with this feature, you probably wouldn't need to use it. You can simply leave the point value for "Attempted, Incorrect" to zero or don't add an a&i response. Then, any question that is not correct whether attempted or left blank will all be worth zero points.)
This feature is available in both the app and the website, although it is only seen in the app when entering the default point values after using the "Scan For Key" option and in the question detail screen on the answer key (pressing the "i" to the far right of a question in the "Edit Key" screen).