VDI, or virtual desktop infrastructure, is a technology that allows the deployment of desktops from virtual machines to user devices and includes components like operating systems, storage, and networking. Key elements of VDI include hypervisors for managing VMs, desktop image management for ensuring desktop configurations, and layered applications for customized user experiences. Networking is vital in VDI to deliver secure desktops to users, necessitating encryption protocols like TLS and SSL.