What exactly is Zulu time used in JAG?

Not long after getting hooked on JAG, I asked a military friend the same question. He told me it is Greenwich Mean Time. As I understood him, it is easier to use GMT, or Zulu, as the common time reference among the military because there are military people in every time zone in the world. This helps cut down on confusion, as does the 24-hour military clock rather than dividing into a.m. and p.m.

OK, tnx.