[libvirt] what does virDomainFree used for?

hi,all i see many virDomainFree, what does it do? thanks ----log-------------- 2013-05-10 02:46:51.315+0000: 1968: debug : virDomainFree:2313 : dom=0x7fbf5c000aa0, (VM: name=longg, uuid=bad73975-ffbc-4ed7-a497-2ca0038c726a) 2013-05-10 02:46:56.319+0000: 1963: debug : virDomainInterfaceStats:7223 : dom=0x7fbf68010ad0, (VM: name=longg, uuid=bad73975-ffbc-4ed7-a497-2ca0038c726a), path=vnet0, stats=0x7fbf808f4b00, size=64 2013-05-10 02:46:56.319+0000: 1963: debug : virDomainFree:2313 : dom=0x7fbf68010ad0, (VM: name=longg, uuid=bad73975-ffbc-4ed7-a497-2ca0038c726a)