There are a few private spaces. The entire 10.x.x.x block is private. You usually see 10.10.x.x for networks using that space. 192.168.x.x is private. Most people seem to use that one. Additionally, 172.16.x.x to 172.31.x.x is also private. Other than that, 127.x.x.x is reserved for lookback addresses and 169.254.x.x is used when your computer automatically assigns itself an address--usually when there is no functioning DHCP server and the node is set to use DHCP. Both of those are private as well. I think that's all of the private space.