This test will check if your site (and finally the server you are hosting) has gzip enabled by connecting to your domain and requesting the necessary information. In addition to this, it will also provide you with some additional information, such as the size of the original version of the tested web page and how much you benefit from using gzip compression. Gzip compression makes it possible to compress web files (mainly HTML, CSS and JS files), sometimes up to 70% -80%. This much smaller version of the file is then sent to the visitor's browser instead of the larger original file. Your visitor's browser will automatically decompress the file and serve the original uncompressed file to your visitor. The Gzipped file has a much smaller size (in bytes) than the original file. The visitor's browser will need less time to load the site because you only have to download much smaller files. How to enable gzip compression. Enable gzip compression using the .htaccess file for Apache You can actually use two different Apache modes to enable HTTP gzip compression: mod_gzip and mod_deflate. Mod_gzip allows gzip compression, and mod_deflate makes it possible to compress from your server before being sent to the visitor (which is the same thing). So, should you compress your resources with gzip or deflate? After all, it doesn't matter much, both modules will give you the same maximum gzip compression as possible. But, as a general rule, it is recommended to use mod_deflate, because it is more widely accepted as mod_gzip. Mod_deflate is also better documented and easier to configure. If mod_deflate does not work on your server, you can still use mod_gzip. Not every company has these modules enabled on its servers. Gzip on Windows servers (IIS Manager) When your site is hosted on a Windows server, you can enable compression for both static and dynamic files. It is quite easy to configure this in the IIS manager: 1. Open IIS Manager 2. Click on the site for which you want to enable compression 3. Click Compression (under IIS) 4. Activate static compression and you're done!