Good coding practice requests well-named variables, spacing and comments in order to enhance readability for your developers. Fair enough, but browsers and web servers do not need these extra human-readable bits that create additional network traffic without providing any functional benefit.
This is why wao.io automatically removes comments and extra spaces from your JS, CSS and HTML files in order to minimize code and reduce file size. The minified version provides the same functionality while reducing the bandwidth of network requests. The development masters still reside on your server and remain easily readable by humans.