Although using decimal numbers for IP addresses is much easier than trying to use (or even remember) 32-bit binary numbers, it is still not as simple as using common English words or names for network hosts. It is much easier to remember the hostname "WWW.UNOVERICA.COM" than it is to remember 206.251.192.80, the IP address of that host at the time of this writing.
Also, IP addresses can change quite often, although host names do not necessarily change with any frequency. There will likely be a host named "WWW.UNOVERICA.COM" for many years to come, although it will also likely change IP addresses several times over the course of the next few years. The address may change because of a new network number assignment, or because the web pages are moved to a different machine, or for any number of other reasons. When this happens, the WWW.UNOVERICA.COM hostname will need to point to a different address.
Regardless of how we humans refer to hosts, the IP stacks themselves always use IP addresses to establish connections. In order for an application to provide the raw IP address to the stack, it must convert the names into addresses on our behalf.
There are two common methods for this. The first method uses text files that simply provide name-to-address lookup maps, which are nothing more than simple databases. The second method uses a global name resolution service called the Domain Name System (DNS), which is essentially a distributed database application that allows host names to be resolved to their IP address, regardless of the host that stores the name-to-address database.
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