How mod_deflate works
When a visitor accesses a website, a request is made to the web server for a specific kind of data. An example might be a home page of a site. Next, the web server locates that data and delivers it to the client who is requesting that data – basically back to the web browser.
In this example, the speed at which the home page loads can depend on a variety of factors. One of them could be how long it takes to find and deliver the data for that page. This is just one example.
Some of that data – such as javascript files, css files, and php files – can actually be compressed into smaller sizes before they are delivered back to the visiting client or browser at the smaller size. The visitor can now have a more optimized browsing experience.
This is where mod_deflate comes in.