These addresses are not routed on the Internet and thus their use need not be coordinated with an IP address registry.
Today, when needed, such private networks typically connect to the Internet through network address translation (NAT). Typically, a network administrator will divide a block into subnets; for example, many home routers automatically use a default address range of 192.168.0.0 through 192.168.0.255 (192.168.0.0/24).
IPv4 addresses are canonically represented in dot-decimal notation, which consists of four decimal numbers, each ranging from 0 to 255, separated by dots, e.g., 1.1.
Each part represents a group of 8 bits (octet) of the address.
Early network design, when global end-to-end connectivity was envisioned for communications with all Internet hosts, intended that IP addresses be uniquely assigned to a particular computer or device.
However, it was found that this was not always necessary as private networks developed and public address space needed to be conserved.
IP addresses are binary numbers, but they are usually stored in text files and displayed in human-readable notations, such as 1.1 (for IPv4), and 2001:db8:34:7:8:1 (for IPv6).
The Internet Assigned Numbers Authority (IANA) manages the IP address space allocations globally and delegates five regional Internet registries (RIRs) to allocate IP address blocks to local Internet registries (Internet service providers) and other entities.
Depending on the class derived, the network identification was based on octet boundary segments of the entire address.
Each class used successively additional octets in the network identifier, thus reducing the possible number of hosts in the higher order classes (B and C).