Starting IP Address Numbers & Meanings

by John Lister Google

An Internet Protocol address is a number that identifies a device in a network, though the term is often used to refer to a device on the Internet itself. An IP address is vital for transferring data from device to device across the Internet, such as when you use your office computer to visit a website. Note that an IP address refers to a device and not to a specific individual.

Public vs. Private

Every IP address works for a specific network: this could be a home or business local network, or the Internet itself. To avoid confusion, the term "private IP address" usually refers to the local network and "public IP address" refers to the Internet. If you have a home network, every device on it has a private IP address. Usually only the router and/or modem have a public IP address. If somebody refers to "your" IP address, the number usually refers to your router and/or modem rather than your specific computer.


Website addresses and IP addresses are not the same thing. Website addresses are made up of letters and numbers, usually beginning with "www" and ending with a domain reference such as ".com" or ".org." The World Wide Web uses a system called DNS, or Domain Name System, that acts a bit like a phone directory and translates the website address into the current IP address where the Web page is moved. This means you can change the server computer where your website is physically located without needing to change your website address.


Most IP addresses use the original system, known as IPv4. This is made up of four numbers, with a dot between each number. The numbers are between zero and 255 in each case. IP addresses are usually issued by Internet service providers when they set up a connection for a customer. Because Internet service providers are allocated a pool of numbers to use, you can sometimes get an idea of the country or region of a device simply by looking at its IP address. However, this doesn't always work. Some IP address number ranges are reserved for specific uses -- for example, those beginning with 192.168 are usually reserved for local networks, and to avoid confusion they are not used on the Internet itself.


The number format used in IPv4 allows for a total of 4.2 billion addresses, which once seemed far more than would ever be needed. As computers and other Internet-enabled devices have become more popular, this has proven not to be the case -- by 2011 all possible IP addresses had been allocated to particular regions of the world. The solution is IPv6, which is set to one day be the main system, though it was still in development as of March 2013. An IPv6 address is made up of eight blocks, each of which has four characters. These are hexadecimal characters, meaning they can be numbers from zero to 9 or letters from "a" to "f." In total IPv6 allows for a possible 340 undecillion -- 340 trillion trillion -- addresses. This should be an adequate long-term solution simply because that number of Internet-enabled devices wouldn't physically fit on Earth.

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