Serving full-time active duty Army

Active duty Soldiers fall into two general categories: enlisted personnel and Officers. Enlisted Soldiers are the backbone of the U.S. Army. Each has his or her own specialized training and fills a role within his or her unit. Officers are the Army's leaders. They guide enlisted Soldiers during missions and provide the know-how and expertise to get the job done. Active duty service terms typically last two to six years. Deployment can last up to a year, but the length may vary depending on a unit's specific mission. Soldiers are eligible for a two-week Rest and Relaxation (R&R) leave after six months of deployment.

 http://www.goarmy.com/about/service-options/active-duty.html