Advanced Individual Training (
AIT) is the second step of most soldiers'
US Army careers. After learning basic skills common to all soldiers in
Basic Combat Training (
BCT), AIT teaches job specific tasks.
AIT and BCT soldiers are referred to as Initial Entry Training (IET) soldiers. AIT and BCT fall under the Training and Doctrine (TRADOC) command.
AIT lasts anywhere from 2 to 20+ weeks, depending on the soldier's Military Occupational Specialty (MOS). The infantry MOSs (usually the 11 and 12 series) usually are among the briefest AITs. Apparently there is not much more to learn outside of the basic soldier stuff taught in BCT. Among the MOSs with the longest AITs are the 97 and 98 series - Military Intelligence. Linguists can go to a school for upwards of a year to learn their language (while this school isn't technically AIT, it is still during IET) and still not be done with their training.
During most AIT programs, Drill Sergeants are still your immediate supervisors. They don't treat you as poorly as in BCT, but you don't get treated as if you were a real soldier, either. While learning job specific tasks, you build upon those basic skills you learned in BCT.