understanding free's output

["Chad A. Adlawan" <caa@archangel.8eight8.net.ph>]

hi List !
  when i invoke free, i get the following :


archangel:~$ free
             total       used       free     shared    buffers     cached
Mem:         63268      12692      50576      22284        944       5824
-/+ buffers/cache:       5924      57344
Swap:       130748          0     130748


  may i know what those 2 entiries in the "-/+ buffers/cache"  stand for ? 
what does those numbers mean ?  i viewed the free man page already and i got
nothing there.

TIA,
Chad