Each offseason, all 32 NFL teams hold a series of voluntary offseason workout programs.
These nine-week programs are conducted in three phases, per the collective bargaining agreement:
Phase One consists of the first two weeks of the program, with activities limited to strength and conditioning and physical rehabilitation.
Phase Two consists of the next three weeks of the program. On-field workouts may include individual player instruction and drills as well as team practice conducted on a "separates" basis. No live contact or team offense versus team defense drills are permitted.
Phase Three consists of the next four weeks of the program. Teams may conduct a total of 10 days of organized team practice activity, or OTAs. No live contact is permitted, but 7-on-7, 9-on-7 and 11-on-11 drills are permitted.
Additionally, clubs may hold one mandatory minicamp for veteran players. This minicamp must occur during Phase Three of the offseason program.