Merit Badges
There are over 130 merit badges that can be earned throughout a boy's Scouting journey. To obtain the Eagle rank, a scout must complete a minimum of 21 merit badges, including 7 "Eagle Required". After obtaining Eagle, an Eagle Scout can continue to earn merit badges and advance through Eagle Palms every 3 months before his 18th birthday.
The full list of merit badges and their requirements are located here.