Each year BOTM has a reading challenge, tracked on their app/site. This is just a way to track it here if you want all of your challenges in one place.
It consists of 1 main badge, 6 bonus badges (complete 3 to get the prize), and a secret badge that unlocks after you get the main badge. (I will add a check off for completing the 3 of 6 bonus badges, but the individual books will be listed under "bonus challenges." This should allow for everyone to complete the 3 they want without having the challenge marked incomplete as a whole.)
Just like with BOTM Challenge, one book can count for the main badge and multiple bonus categories.