Every machine on a network has a unique identifier. Most computers and networks use the TCP/IP protocol as the standard for communicating on a network, which uses an IP address to identify a computer. An Internet Protocol address, or an IP address, is a numerical label assigned to each device connected to a computer network that uses the Internet Protocol for communication.
There are two standards for IP addresses. IP Version 4 (IPv4) and IP Version 6 (IPv6). IPv4 uses 32 binary bits to create a single unique address on the network. An IPv4 address is expressed by four numbers separated by decimals. IPv6 uses 128 binary bits to create a single unique address that is expressed by eight groups of hexadecimal numbers separated by colons. All computers with IP addresses have an IPv4 address and many are starting to incorporate the newer IPv6 addresses.
There are about 4.294 billion IP addresses the IPv4 protocol, 600 million of which are reserved and cannot be used for public routing. The Internet Assigned Numbers Authority (IANA) allocates the rest of the IP addresses to countries. Allocation does not necessarily correlate with population numbers.
Of the over 4 billion IP addresses, 1,541,605,760 are allocated to the United States, the highest number of any country. This comes out to about 4,911 IP addresses per 1,000 people. These comprise about 35.9% of the total number of IP addresses.
China has the second-highest number of IP addresses of 330,321,408, about 7.7% of the total number of IP addresses. China is followed by Japan with 202,183,168 and the United Kingdom with 123,500,144. Germany has the fifth-highest number of IP addresses with 118,132,104.
Vatican City, which has the smallest population of any sovereign state of fewer than 1,000 people, has 17,920 IP addresses. This equates to 21,435 IP addresses per 1,000 people.
Factored into the 4.294 million IP addresses are over 875 million bogons, which are bogus (or fake) IP addresses on a computer network. Bogons include IP packets with addresses that are not in any range allocated or delegated by the IANA. Most Internet service providers and firewalls filter out bogons as they have no use and are usually the result of accidental or malicious misconfiguration.
Below is the number of IP addresses in every country, as well as the number of IP addresses 1,000 people in the population and the percentage of total IP addresses each country possesses.