How to enable gzip compression.
Website gzip compression makes it possible to reduce the file size of a web file (like HTML, PHP, CSS and Javascript files) to about 30% or less of its original size before these files get sent to the browser of a user. This compressed file is then served to the browser of the user which in turn decompresses it automatically to load the full original file in the browser again. Enabling gzip compression is great for improving page speed because your visitors will need to download much smaller web files as the original ones when browsing your web pages , which speeds up the download process of these files. There’s no reason to not use it these days.

Enable gzip compression using the .htaccess file for Apache
You can actually use two different Apache mods to enable HTTP gzip compression: mod_gzip and mod_deflate. Mod_gzip enables gzip compression and mod_deflate makes it possible to compress the output from your server before it is being sent to your visitor (which is the same thing). So should you be compressing your resources with gzip or deflate? In the end it doesn't matter much, both modules will provide you with the same maximum gzip compression possible. But, as a general rule it is recommended to use mod_deflate since it’s more widely supported as mod_gzip. Mod_deflate is also better documented and easier to configure. If mod_deflate doesn't work on your server you can still use mod_gzip. Not every host has these modules enabled on their servers, so make sure you ask your host about this when the below .htaccess scripts do not work. Add one of the below scripts to your .htaccess file (which can be found or should be placed in the root folder of your website (usually /var/www/html)):
To enable mod_deflate(recommended):
<IfModule mod_deflate.c>
AddOutputFilterByType DEFLATE text/html
AddOutputFilterByType DEFLATE text/css
AddOutputFilterByType DEFLATE text/javascript
AddOutputFilterByType DEFLATE text/xml
AddOutputFilterByType DEFLATE text/plain
AddOutputFilterByType DEFLATE image/x-icon
AddOutputFilterByType DEFLATE image/svg+xml
AddOutputFilterByType DEFLATE application/rss+xml
AddOutputFilterByType DEFLATE application/javascript
AddOutputFilterByType DEFLATE application/x-javascript
AddOutputFilterByType DEFLATE application/xml
AddOutputFilterByType DEFLATE application/xhtml+xml
AddOutputFilterByType DEFLATE application/x-font
AddOutputFilterByType DEFLATE application/x-font-truetype
AddOutputFilterByType DEFLATE application/x-font-ttf
AddOutputFilterByType DEFLATE application/x-font-otf
AddOutputFilterByType DEFLATE application/x-font-opentype
AddOutputFilterByType DEFLATE application/vnd.ms-fontobject
AddOutputFilterByType DEFLATE font/ttf
AddOutputFilterByType DEFLATE font/otf
AddOutputFilterByType DEFLATE font/opentype
# For Olders Browsers Which Can't Handle Compression
BrowserMatch ^Mozilla/4 gzip-only-text/html
BrowserMatch ^Mozilla/4\.0[678] no-gzip
BrowserMatch \bMSIE !no-gzip !gzip-only-text/html
</IfModule>

 
To enable mod_gzip(second back up choice):
<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 mime ^application/x-javascript.*
mod_gzip_item_include mime ^text/.*
mod_gzip_item_exclude rspheader ^Content-Encoding:.*gzip.*
mod_gzip_item_exclude mime ^image/.*
mod_gzip_item_include handler ^cgi-script$
</ifModule>
 OR
# BEGIN GZIP
<ifmodule mod_deflate.c>
AddOutputFilterByType DEFLATE text/text text/html text/plain text/xml text/css application/x-javascript application/javascript
</ifmodule>
# END GZIP