The Agora SDK has introduced a virtual background extension that allows users to apply colors, images, or blur effects to their video call backgrounds. This blog post demonstrates how to use this extension with the Agora Web UIKit. To get started, developers need an Agora developer account and Node.js LTS installed on their systems. They should also have a basic understanding of React. The tutorial provides code snippets for using the extension without the UIKit as well. The virtual background feature is made performant by using a WebAssembly module that needs to be hosted separately or bundled with the website.