Continuing to take advantage of the Apache web server, we will activate the mod_expires module. This module sends a message to the client machine about the document's validity, and the client can store a cache of the site until the client receives a new message from the server expiration of data. This technique increases the speed of download.
To activate this feature, you can open the .htaccess file available in the Magento root directory and enter this block of code:
<IfModule mod_expires.c>
############################################
## Add default Expires header
## http://developer.yahoo.com/performance/rules.html#expires
ExpiresActive On
ExpiresDefault "access plus 1 year"
</IfModule>For further information about the .htaccess configuration, follow the link at http://httpd.apache.org/docs/2.2/mod/mod_expires.html.