Private and Public Networks and IP addresses and CIDR

Internet is a Public network, 

So that IP addresses in private networks do not clash with IP addresses on the internet(public network), some particular IP range are reserved for the purpose of private networking

• Reserved IP ranges(CIDR) for private networking and this CIDR is never given to computers on the public internet
• 10.0.0.0/8
• 172.16.0.0/12
• 192.168.0.0/16
• Obviously multiple private networks can have the same CIDR but you can not interconnect two private networks having the same CIDR