Your host file enables your system to override the DNS setting for a domain. This change only affects your system.
The syntax of a host file entry is as follows
# this is a comment 192.168.22.22 molecularsciences.org
Basically you specify an IP followed by a domain. All lines beginning with # sign are comments.
Host files should only be edited with plain text editors like notepad, notepad++, sublime, etc. Following are the locations of host files on different systems:
|Operating System||Host file location|