These are private IP address range as described in RFC 1918. They are not routed on the internet and they are for private or internal use only.
10.0.0.0 – 10.255.255.255Â Â Â Â Â Â or 10.0.0.0/8
172.16.0.0 – 172.31.255.255Â Â Â Â or 172.16.0.0/12
192.168.0.0 – 192.168.255.255Â or 192.168.0.0/16
Source:
ftp://ftp.rfc-editor.org/in-notes/rfc1918.txt