What does a collision mean?
Staff Sgt. Shawn Meyer teaches a lesson on computer hubs and switches for members of the 100th Communications Squadron at RAF Mildenhall. Sergeant Meyer is a member of the 175th Communications Squadron, Maryland Air National Guard. He works for Microsoft, Inc as a civilian. June 20, 2008. (U.S. Air Force Photo by Senior Master Sgt. Bill Harkum)