We discussed ways to optimize the total web-page transfer size and the reasons to do so. It is a broad subject and a good starting point to learn more is to start using Google's PageSpeed Insights Browser Extensions (available at https://developers.google.com/speed/pagespeed/insights_extensions). Note that the versions for Firefox and Chrome work a bit differently, so it may be worth looking at both. Besides the ability to quickly review possible page-speed delays, it provides tips on how to speed up your page. One should not take those tips as a religion. For example, a standard tip we will see on each responsive page is "Specify image dimensions"—something that we definitely shouldn't do in this case.
In the next chapter you will learn how to create and use jQuery plugins, capable of turning elements of your page into interactive responsive components.