The goal of JavaScript and CSS minification is always to preserve the operational qualities of the code while reducing its overall byte footprint (both in raw terms and after gzipping, as most JavaScript and CSS served from production web servers is gzipped as part of the HTTP protocol). The YUI Compressor is JavaScript minifier designed to be 100% safe and yield a higher compression ratio than most other tools. Tests on the YUI Library have shown savings of over 20% compared to JSMin (becoming 10% after HTTP compression). The YUI Compressor is also able to compress CSS files by using a port of Isaac Schlueter's regular-expression-based CSS minifier.