With CORS, you can securely upload files directly into an S3 bucket, directly from the browser, without using an intermediate proxy (e.g. your web server).
HTML5 and ccs3 are a really loud buzz in web design for quite some time. The new features can be really powerful tools in a developer’s arsenal. This technology can also be used in all sort of mobile devices. All modern devices have browsers that support all those new exciting features.