One of three ways of becoming a commissioned officer in the US Air Force. The others are the Air Force Academy and officer training school (OTS). Very similar to other ROTC programs, in that people become cadets in civilian colleges, and are required to attend some sort of military education program as well as their normal college curriculum. Some join AFROTC to become pilots, to serve their country, or just for the opportunity to have their tuition paid for by the Air Force.
AFROTC cadets begin their careers as GMC (General Military Course) in which they learn basic skills like marching, wearing their uniform, and some knowledge about the Air Force. At the end of their second year, they will attend a field training encampment, after which (if they pass), they will enter the POC (Professional Officer Course). As a POC, a cadet will take a leadership roll over the GMC in the corps, and will begin to prepare for active duty service after they get their degree.
Cadets have two main responsibilities in AFROTC: attending Aerospace Studies classes and attending leadership laboratory (LLAB). Aerospace Studies classes teach cadets about Air Force history, regulations, and officer responsibilities, and generally meet once a week. LLABs give cadets a chance to flex their leadership or followership roles in a real life setting, as cadets are responsible for running all parts of corps life (with the help of officer cadre).