What this ifconfig output telling me?

What is this output of ifconfig telling me? Any explanation of the first in particular would be sweet.

A:~ Linda$ ifconfig

lo0:  flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> mtu 16384
      options=3<RXCSUM,TXCSUM>
      inet6 ::1 prefixlen 128 
      inet 127.0.0.1 netmask 0xff000000 
      inet6 fe80::1%lo0 prefixlen 64 scopeid 0x1 
      nd6 options=1<PERFORMNUD>

gif0: flags=8010<POINTOPOINT,MULTICAST> mtu 1280

stf0: flags=0<> mtu 1280

en0:  flags=8822<BROADCAST,SMART,SIMPLEX,MULTICAST> mtu 1500
      options=2b<RXCSUM,TXCSUM,VLAN_HWTAGGING,TSO4>
      ether 00:1e:c2:1d:0c:15 
      media: autoselect
      status: inactive

en1:  flags=8863<UP,BROADCAST,SMART,RUNNING,SIMPLEX,MULTICAST> mtu 1500
      ether 00:1e:c2:ba:ce:23 
      inet6 fe80::21e:c2ff:feba:ce23%en1 prefixlen 64 scopeid 0x5 
      inet 192.168.1.2 netmask 0xffffff00 broadcast 192.168.1.255
      nd6 options=1<PERFORMNUD>
      media: autoselect
      status: active

fw0:  flags=8822<BROADCAST,SMART,SIMPLEX,MULTICAST> mtu 4078
      lladdr 00:1f:5b:ff:fe:13:0d:f0 
      media: autoselect <full-duplex>
      status: inactive