from
The Free On-line Dictionary of Computing (8 July 2008)
hosts file
<networking> A {text file} on a networked computer that was
used to associate {host names} with {IP addresses}. A hosts
file contains lines consisting of {whitespace}-separated
fields giving an IP address followed by list of host names or
{aliases} associated with that address. The {name resolution}
library software can use this file to look up the IP address
for a host name. The hosts file is "/etc/hosts" on {Unix} and
"C:\Windows\System32\drivers\etc\hosts" or "lmhosts" on
{Microsoft Windows},
Hosts files have now been almost entirely replaced by {DNS},
in which distributed servers provide the same information.
A hosts file can still be used to override DNS for testing
purposes or other special situations.
(2007-05-09)