Virtual desktop infrastructure (VDI) is a way of running an employee's desktop on a server in a data centre or the cloud, and streaming it to whatever screen the employee sits at. The employee sees a normal Windows desktop. But the programs and the files are on the server, not on the employee's device. When a company rents such desktops from a cloud provider, it is called desktop as a service, or DaaS.
Here is how it works. The servers in the data centre run many virtual machines. A virtual machine is a complete computer made of software, and many of them can share one physical server. Each one runs one employee's desktop. The employee's device runs only a small client app. The app receives images of the desktop and sends back the employee's key presses and mouse clicks. So the customer data shown on the screen never leaves the data centre.
When the employee logs in, a program called a connection broker finds a free desktop for that employee. Employees outside the office first pass through a secure gateway, which checks who they are. This is often done with zero trust network access (ZTNA), which connects each user to one application only. When thousands of employees log in at 9 a.m., a load balancer spreads them across the servers.
Consider a customer-support centre in Mohali where 300 support executives answer calls for a credit card company. Their screens show customers' card details and home addresses. Each executive sits at a thin client, a small, cheap computer with no hard disk. The executive's desktop, with its contact centre software, runs on servers in the company's data centre in Noida. The desktops block copying files to a USB drive. If a thin client breaks, the executive moves to the next seat, logs in, and finds the same desktop, with the same call screen open. On weekends, some executives work from home in Ludhiana on their own laptops. If one of those laptops is stolen, no customer data is on it.
VDI has costs. It needs a good network connection, because every screen image travels over it. If the data centre or the network fails, nobody can work. Video calls and 3D design need extra server power. And the servers and licences cost money, which an ordinary laptop does not. So companies use VDI mainly where data protection matters most, such as call centres, banks and hospitals. Digital employee experience (DEX) software measures how quickly each virtual desktop responds.
VDI is different from remote desktop software. Remote desktop software lets a technician control an existing computer for a short time. With VDI, the employee's desktop always lives on the server.