What is an IP address?

Every machine on the Internet has a unique identifying number, called an IP Address. A typical IP address looks like this:

To make it easier to remember, IP addresses are normally expressed in decimal format as a ‘dotted decimal number’ as illustrated above.


An easy way to understand what an IP address is to compare it to a postal address. The IP address contains the country, county, town, street and building number. With this information, data can be routed to all machines. If a machine has no IP address, no data will be able to reach it.