The use of IP addresses, whether IPv4 or IPv6, is the primary means of enabling devices to locate one another and establish end-to-end communication on the Internet. In fact, in any internetwork, IP addresses are essential for devices to communicate from source to destination and back.

Each end device on a network must be configured with IP addresses. Some examples of end devices are:

The structure of an IPv4 address is called dotted decimal notation and is represented with four decimal numbers between 0 and 255. IPv4 addresses are numbers assigned to individual devices connected to a network. They are logical in nature, in that they provide information about the location of the device.

With the IP address, a subnet mask is also necessary. A subnet mask is a special type of IPv4 address that, coupled with the IP address, determines which particular subnet of a larger network the device is a member.

IP addresses can be assigned to both physical ports and virtual interfaces on devices. A virtual interface means that there is no physical hardware on the device associated with it.