php - Leverage browser caching, how on apache or .htaccess?

Question

What to do here? I have a huge list of files that Google Speed Page said to "Leverage Browser Caching".. but I don't know how? Do I mess or change the Apache config file (below) or do I put something in my .htaccess page?

 <IfModule mod_proxy.c>
        ProxyRequests Off
        CacheRoot "/var/run/proxy"
        CacheSize 1024
        CacheGcInterval 24
    #CacheMaxExpire 24
    #CacheLastModifiedFactor 0.1
    #CacheDefaultExpire 1
    #NoCache a_domain.com another_domain.edu joes.garage_sale.com
        <Directory "disabled_proxy">
            Allow from example.com
            Deny from all
            Order Deny,Allow
        </Directory>
    </IfModule>
    ##
    #### mod_expires is configured so that all static files but images
    #### expire after 60 seconds. Any response that has a life span of more
    #### than 5 seconds (see webperfcache.conf) will be cached by webperfcache.
    #### Make sure your CGIs return a "Cache-Control: no-cache" header if you
    #### elect to make your dynamically generated HTML pages not cache-able.
    #### If all your HTML pages are static you may also increase ExpiresDefault.

    <IfModule mod_expires.c>
        ExpiresActive On
        ExpiresDefault A60
        ExpiresByType image/bmp A3600
        ExpiresByType image/gif A3600
        ExpiresByType image/ief A3600
        ExpiresByType image/jpeg A3600
        ExpiresByType image/png A3600
        ExpiresByType image/tiff A3600
        ExpiresByType image/x-cmu-raster A3600
        ExpiresByType image/x-portable-anymap A3600
        ExpiresByType image/x-portable-bitmap A3600
        ExpiresByType image/x-portable-graymap A3600
        ExpiresByType image/x-portable-pixmap A3600
        ExpiresByType image/x-rgb  A3600
        ExpiresByType image/x-xbitmap A3600
        ExpiresByType image/x-xpixmap A3600
        ExpiresByType image/x-xwindowdump A3600
        ExpiresByType audio/basic A3600
        ExpiresByType audio/midi A3600
        ExpiresByType audio/mpeg A3600
        ExpiresByType audio/x-aiff A3600
        ExpiresByType audio/x-pn-realaudio A3600
        ExpiresByType audio/x-pn-realaudio-plugin A3600
        ExpiresByType audio/x-realaudio A3600
        ExpiresByType audio/x-wav A3600
        ExpiresByType video/mpeg A3600
        ExpiresByType video/quicktime A3600
        ExpiresByType video/x-msvideo A3600
        ExpiresByType video/x-sgi-movie A3600
    </IfModule>

Answer 1

I took my chance to provide full .htaccess code to pass on Google PageSpeed Insight:

1. Enable compression
2. Leverage browser caching

# Enable Compression
<IfModule mod_deflate.c>
  AddOutputFilterByType DEFLATE application/javascript
  AddOutputFilterByType DEFLATE application/rss+xml
  AddOutputFilterByType DEFLATE application/vnd.ms-fontobject
  AddOutputFilterByType DEFLATE application/x-font
  AddOutputFilterByType DEFLATE application/x-font-opentype
  AddOutputFilterByType DEFLATE application/x-font-otf
  AddOutputFilterByType DEFLATE application/x-font-truetype
  AddOutputFilterByType DEFLATE application/x-font-ttf
  AddOutputFilterByType DEFLATE application/x-javascript
  AddOutputFilterByType DEFLATE application/xhtml+xml
  AddOutputFilterByType DEFLATE application/xml
  AddOutputFilterByType DEFLATE font/opentype
  AddOutputFilterByType DEFLATE font/otf
  AddOutputFilterByType DEFLATE font/ttf
  AddOutputFilterByType DEFLATE image/svg+xml
  AddOutputFilterByType DEFLATE image/x-icon
  AddOutputFilterByType DEFLATE text/css
  AddOutputFilterByType DEFLATE text/html
  AddOutputFilterByType DEFLATE text/javascript
  AddOutputFilterByType DEFLATE text/plain
</IfModule>
<IfModule mod_gzip.c>
  mod_gzip_on Yes
  mod_gzip_dechunk Yes
  mod_gzip_item_include file .(html?|txt|css|js|php|pl)$
  mod_gzip_item_include handler ^cgi-script$
  mod_gzip_item_include mime ^text/.*
  mod_gzip_item_include mime ^application/x-javascript.*
  mod_gzip_item_exclude mime ^image/.*
  mod_gzip_item_exclude rspheader ^Content-Encoding:.*gzip.*
</IfModule>

# Leverage Browser Caching
<IfModule mod_expires.c>
  ExpiresActive On
  ExpiresByType image/jpg "access 1 year"
  ExpiresByType image/jpeg "access 1 year"
  ExpiresByType image/gif "access 1 year"
  ExpiresByType image/png "access 1 year"
  ExpiresByType text/css "access 1 month"
  ExpiresByType text/html "access 1 month"
  ExpiresByType application/pdf "access 1 month"
  ExpiresByType text/x-javascript "access 1 month"
  ExpiresByType application/x-shockwave-flash "access 1 month"
  ExpiresByType image/x-icon "access 1 year"
  ExpiresDefault "access 1 month"
</IfModule>
<IfModule mod_headers.c>
  <filesmatch ".(ico|flv|jpg|jpeg|png|gif|css|swf)$">
  Header set Cache-Control "max-age=2678400, public"
  </filesmatch>
  <filesmatch ".(html|htm)$">
  Header set Cache-Control "max-age=7200, private, must-revalidate"
  </filesmatch>
  <filesmatch ".(pdf)$">
  Header set Cache-Control "max-age=86400, public"
  </filesmatch>
  <filesmatch ".(js)$">
  Header set Cache-Control "max-age=2678400, private"
  </filesmatch>
</IfModule>

There is also some configurations for various web servers see here.
Hope this would help to get the 100/100 score.