An IP Address (aka Internet Protocol Address) is an exclusive number all information technology devices (computers, printers, routers, modems, etc…) use which identifies and allows them the ability to communicate with each other on any Transmission Control Protocol/Internet Protocol (TCP/IP) based computer network. There is a standard of communication which is called an Internet Protocol standard (IP). A simple common analogy would be your street address. In order for you to receive snail mail at home the sending party must have your correct mailing address (IP address) in your city (network) or you do not receive your mail. The same is true for all equipment on the internet. Without this specific address, information cannot be properly routed or received. IP addresses may either be assigned permanently (known as Static IPs) as in the case of an email or web hosting server or dynamically, from a pool of available addresses (first come first serve) from a Dynamic Host Control Protocol(DHCP) server located at your internet service provider (ISP). A static IP may not be available in all cases and may cost extra so be sure to ask your ISP.
Domain Name Servers (DNS) allows the IP address to be translated to letters and numbers or even words, that are easier for humans to remember. For example, it is much easier for us to remember a web address name such as prod.net than it is to remember 192.168.1.1 or in the case of email it is much easier to remember email@example.com than firstname.lastname@example.org
I mentioned that you IP address may be either dynamic or static. A dynamic IP Address is an IP address that most likely changes every time you log in. If you remain logged in long enough it may change occasionally while you are logged in. This is based on how your ISP has configured their DHCP servers. A dynamic IP address is issued to you from a pool of IP addresses allocated by a DHCP Server. This is for a large number of customers that do not require the same IP Address all the time for a variety of reasons. Your computer will automatically get this number as it logs on to the network. This saves you the trouble of having to know or configure all the details regarding the specific network configurations. This number can be assigned to anyone using a dial-up connection, wireless and high speed internet connection. If you need to run your own email server or any web based server, it is best to have a static IP. A Static IP Address is an IP address that is fixed and never changes. This is in contrast to a dynamic IP address which may change at any time. Most ISP’s a limited number of static IP addresses available to them. For this reason they most commonly assign dynamic ip addresses or charge a few extra bucks a month if a customer requests a static ip address. All the same concepts apply to dynamic or static ip addresses on a local (LAN) or wide area network(WAN) as well. In these cases, the dynamic IP addresses are generated by the DHCP server most commonly built into a router. It is also important to understand that if your ISP only assigns you one IP address, either dynamically or static, and you configure a device such as your router to act as your internal or local DHCP server, then even though you may have several devices each with there own IP address on you LAN, you are only using one IP address on the internet. Going back to the analogy of your city street address, you can think of LAN IP addresses like apartment numbers. Inside the apartment building you are apartment 10.10.10.16, but you still have a street address of 126.96.36.199. This is why when you do an IPCONFIG you may see one IP address, but when you go to a site such as http://www.myipaddress.com it may display a different IP address.
The IP has three versions that you should be aware of. IP version 4 (IPv4) is currently used by most network devices. However, with more and more computers and other devices accessing the internet, IPv4 addresses are running out quickly. Just like in a city, addresses have to be created for new neighborhoods but, if your neighborhood gets too large, you will have to come up with an entire new pool of addresses. IPv4 is limited to 4,294,967,296 addresses. IP version 5 is an experimental protocol for UNIX based systems. In keeping with standard UNIX (a computer Operating System) release conventions, all odd-numbered versions are considered experimental. It was never intended to be used by the general public. IP version 6 (IPv6) is the replacement for the aging IPv4. The estimated number of unique addresses for IPv6 is 340,282,366,920,938,463,463,374,607,431,768,211,456 or 2^128.
The old and current standard of addresses was this: 192.168.100.100
the new way can be written different ways but means the same and are all valid: