Enabling gzip allows compression of HTML,CSS and other specified files. This saves a lot of file size, saving bandwidth as a result. When your site requires less bandwidth, it will load faster.
To enable gzip you must add the following lines of code to your .htaccess file.
AddOutputFilterByType DEFLATE text/css text/x-component application/x-javascript application/javascript text/javascript text/x-js text/html text/richtext image/svg+xml text/plain text/xsd text/xsl text/xml image/x-icon application/json