The Unit is a U.S. Army organization of unknown size, similar to Delta Force. As with Delta Force, its members come from the United States Army and appear to be primarily tasked with counterterrorism. The unit's official cover is as the "303rd Logistical Studies Group". In the third season's premier, an onscreen read-out specifically identifies the unit as "ALPHA Team 1st Special Actions Group".
The Unit is based at a fictional army post, "Fort Griffith".
The unit's immediate chain of command goes to the commanding officer, Colonel Tom Ryan — and, presumably, straight to the President of the United States. It is unknown if this bypasses the Secretary of Defense.
The wives of the unit's personnel are given minimal information. They are fully aware of the fact that "The Unit" is a false front organization, and that their husbands are, in fact, still performing highly dangerous missions, but they are not permitted to know specifics, such as where their husbands are deployed, what their training routines consist of, how long their assignments will last, or even if their husbands are safe.