The conflicts in Iraq and Afghanistan have introduced a large, new vocabulary of acronyms and abbreviations into the American experience of war: GWOT, GSAVE, IED, SVBIED, MOAB, OEF, OIF and on and on. But perhaps the most important for understanding the soldier's experience during the war on terrorism is FOB, the term for the more than 100 forward operating bases where the majority of soldiers and airmen in Iraq and Afghanistan are stationed. FOBs provide the infrastructure of American presence in the theater, ranging from massive air bases into which men and materiel flow to the staging outposts from which daily vehicle patrols and combat operations are launched.

http://www.armedforcesjournal.com/2006/06/1813596