 You can make your website faster and use less data by making sure you don't request files you don't need. This web page works fine on my laptop on fast broadband, but let's try loading it on a mobile phone on 3G. Now, this is the kind of experience most of your users will get, and that's not so good. Let's see what's going on. One really easy way to find website problems is to check the Chrome DevTools Network Panel and filter by type. Wow, that's a lot of files and a lot of bytes. The individual JavaScript files may not be very large, but each file needs to be parsed and executed, and means another request to the server, which can slow down your site and use battery. Let's check what's going on. Straight away you can see a problem. I'm linking to multiple different versions of jQuery. Now, it gets worse. I've linked to the full FAT version as well as the minimized one. Let's get rid of the files we don't need. You should only ever link to one version of a JavaScript library. Cutting out unnecessary JavaScript makes your website more reliable, easier to maintain, and simpler to debug. Let's see what else is going on. Now, Chrome DevTools has a great feature for finding CSS or JavaScript that's never used. From more tools, select coverage, and then start recording as you use the site. I'll use the site for a while and then see what the coverage tool finds. So let's stop recording and look at the results. Now, one thing that really stands out, some CSS and JavaScript files aren't being used at all. Now, it turned out I forgot to remove links to files I used earlier in the project. I can get rid of those straight away, and that's a big weight reduction and less file requests, all without changing any code. Getting rid of unused code also makes your site easier to debug and reduces the amount of code the browser needs to parse and execute. I hope that was useful. Take a look at our other videos for more tips to make your website even faster.