U.S. Army Advanced Individual Training, or AIT, takes place after the successful completion of Basic Combat Training and is effectively vocational training for the soldiers in their assigned military occupational specialties, or MOSs. Soldiers can expect a combination of learning in a classroom environment and hands-on training in the field.
Some military occupational specialties, particularly the military police or those that are heavily focused on battlefield roles such as infantry, may have their AIT training combined with basic training and conducted on the same site with the same drill instructors. These forms of AIT are referred to as One Station Unit Training and are likely to have living conditions and a daily structured regimen that are similar to those of basic training. Soldiers that move on to AIT at a separate duty station can expect living conditions with more privacy and liberty than they had at basic training.
Depending on the complexity of the MOS, AIT can last from three weeks to nearly two years. The "phase" program from basic training is continued with soldiers beginning in Phase IV and gradually earning their way into Phase V. Phase V includes a number of liberties and privileges such as off-base and overnight passes, varying by duty location.