Private network IPv4 addresses (rfc1918):
Class A: 10.0.0.0 - 10.255.255.255 | 10.0.0.0/8
Class B: 172.16.0.0 - 172.31.255.255 | 172.16.0.0/12
Class C: 192.168.0.0 - 192.168.255.255 | 192.168.0.0/16

Carrier NAT IPv4 private addresses (rfc6598):
100.64.0.0 - 100.127.255.255/10 | 100.64.0.0/10

Test Networks (rfc5735):
TEST-NET-1: 192.0.2.0 - 192.0.2.255 | 192.0.2.0/24
TEST-NET-2: 198.51.100.0 - 198.51.100.255 | 198.51.100.0/24
TEST-NET-3: 203.0.113.0 - 203.0.113.255 | 203.0.113.0/24
Benchmarks: 198.18.0.1 - 198.19.255.255 | 198.18.0.0/15

Private network IPv6 addresses (rfc4193):
Unique local addresses: fd00::/8