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What are IP Addresses?

IP addresses are an essential item in the world of networking, no matter whether it is a small home network, a local area network in a company, or a global network such as the Internet. A network is a number of computers that are physically connected to be able to communicate with each other and exchange data. But in order for them to be able to communicate, they need to speak a common language in order to bridge the gap between different operating systems etc. It enables a web server running UNIX to send data to your PC running Windows in a format that Windows can understand and use. This common language ensures that the data sent by one computer, and the form it was sent in, can be understood and used by the receiving computer. The common language used is called a protocol. There are several protocols available, but one of the most important and most common ones is TCP/IP, which stands for Transmission Control Protocol/Internet Protocol.

But speaking a common language is not enough. In addition, each computer on a network has to be uniquely identifiable for the single reason that the computer who sends data knows where to send it to and vice versa the computer who requests data, needs to know where it is coming from so it knows where to request data from. For that purpose, every computer on a network is assigned a unique number, which is called an IP address.

Think of it as your phone number. In order to talk to your friend on the phone, you both have to have a physical connection, the phone company's network. But to be able to connect to your friend on the phone, you need to identify to the network who you want to talk to. This is done by a unique number, your friend's phone number that is unique to his phone. Same thing with IP addresses and computers.

An IP address is a 32-bit number, divided by periods into 4 groups. Each group is called either an octet because it consists of 8 bits, or a byte because one byte equals 8 bits. An IP address could look like this:

An IP address actually contains two pieces of information. The first part of the IP address contains the network ID. It uniquely identifies a network within a group of different networks. The second part of the IP address contains the host ID. It uniquely identifies a computer within a group of computers on the same network.

An easy way to find out your current IP address is to go to Start/Run, type winipcfg and click OK. In the resulting window you'll see your IP address listed. If you have more than one adapter installed on your system, e.g. a network card and a modem, then you can select from the drop-down menu to see the different IPs.