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's immediate chain of command goes to the commanding officer, Colonel Tom Ryan -- and, apparently, 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.

If a member of the Unit is killed in action, the family is told that they have been killed on a training mission. The wives themselves are encouraged to form a close, cohesive military family based on the mutual knowledge and strife this inevitably leads to.

The Unit has an unconventional structure. While it appears to be the size of a single company, which ranges in size from 60 to 250 personnel, it is commanded by a colonel (companies are usually commanded by captains; colonels usually command elements like brigades). The CO Colonel Ryan, normally wears a "sanitized" uniform (bearing absolutely no tapes, such as his name, or even U.S. Army, or rank insignia).

Whereas a Special Forces ODA (Operational Detachments Alpha) is generally commanded by a captain, the Unit sends teams and squads into the field under the command of noncommissioned officers, such as the team normally commanded by Sergeant Major Jonas Blane, the Unit's Alpha team NCOIC. It is probable that their Soldiers have the same Special Forces specialties as in other Special Forces organizations. An Operational Detachment Alpha (ODA, formerly known as an "A-Team") has weapons sergeants, engineering sergeants, medical sergeants, communications sergeants, intelligence sergeants and operations sergeants.

The wives, if suspected of speaking about the Unit's existence through such endeavours as gossip, can cause their husbands to be expelled, and returned to regular Army service (even if with another Special Forces unit). Colonel Ryan has stated, time and again, that this can ruin a soldier's career, as well as their marriage, and has also stated that he will not hesitate to destroy families, in order to preserve the Unit's security. He has also threatened the wives with closing the Unit down, and restarting it someplace else under another cover, and forcing the uprooting of all families involved.

The Unit deploys throughout the world, and both the Army and United States government have the ability to deny the existence of the Unit and any of its members in order to prevent the onset of international incidents. Their uniforms are commonly not standard Army issue, which makes it easier to deny their connection with the US Army if killed or captured. They also carry weapons that are not always standard-issue. Like all Special Forces units, the Unit's personnel are well-familiarized with weapons from around the world and can make themselves look like military personnel from other organizations.

The Unit's members will frequently use code-names around non-Unit associated people, such as Mr. White, Mr. Black, Mr. Blue or Mr. Green. According to Jonas Blane, the order of precedence for his team after he is disabled, is, from top to bottom: Mack Gerhardt, Charles Grey, Hector Williams, and Bob Brown.