Merit badges cover a wide variety of topics: Outdoor Skills and Adventure, Science and Nature, Health and Safety, Skills, Trades, and Careers, Information Technology and Communication, Business, Education, and Entrepreneurship, History and Culture, Fine Arts and Crafts, Hobbies and Interests.
There are more than 100 merit badges. Any Scout may earn any merit badge at any time, but rank advancement at the lower levels would be more of a priority. Summer camp and other one-day events offer merit badge classes.
For more information: Merit Badges | Scouting America