mod_expires it will caches the page content to the visitors temporary files it may reduce on your Server from High Bandwidth Usage & also the files transferring load
the following is code where you can put into your .htaccess if you we Web Host Customer
or if you are a Server Administrator and want to apply the Mod_expires to all hosts please copy & paste the following to /usr/local/apache/conf/httpd.conf
# turn on the module for this directory
# cache common graphics for 7 days
ExpiresByType image/jpg "access plus 7 days"
ExpiresByType image/gif "access plus 7 days"
ExpiresByType image/jpeg "access plus 7 days"
ExpiresByType image/png "access plus 7 days"
if you want to verify that you have mod_expries installed run from your ssh as root the following