Display identity: EDID
EDID, the Extended Display Identification Data, is the small block of data a display stores and reports to the system it is plugged into: the maker and model, the physical size of the panel, the resolutions and refresh rates it accepts and, when the maker fills them in, the unit's own identifier and the week and year it was made. Websites, installed software and every virtual machine inherit that introduction, and this stop of the tour shows what it gives away.
What EDID is
When a display is connected, the host does not guess what is on the other end of the cable. The display answers with a small block of data called EDID. The manufacturer writes it once and stores it in the display itself. The block names the maker and the model, describes the physical size of the panel and its color characteristics, and lists the resolutions and refresh rates the panel accepts. It can also carry an identifier of the individual unit together with the week and year it was made; those fields are optional, and some makers leave them empty or record a model year instead of a manufacture date.
How websites see it
A web page cannot read the block itself, but it sees its consequences. The browser tells scripts the size of the screen in pixels, the pixel density, the color depth, the orientation and the size of the window against the screen, and all of that descends from what the display reported. Scripts that profile visitors combine these values with dozens of other signals into a fingerprint of the visitor's system. They also look for combinations that no real monitor produces: a screen whose size matches no panel on the market, a pixel density that does not fit the reported resolution, a window larger than the screen that supposedly holds it. A display identity that is plausible and stays the same from one visit to the next is therefore the first thing a visitor's system is judged by.
How installed software sees it
Programs installed on the system are not limited to the browser's summary: through the operating system they read the block itself, with the maker, the model, the unit identifier and the manufacture date. Many desktop applications, launchers and security components of online services do exactly that when they decide whether they are running on a real PC. The display is one of the first things they check, because it is cheap to read and hard to fake by accident.
Why it matters for a virtual machine
A virtual machine normally has no monitor at all. Its display adapter is a piece of software, and the identity it reports is generic: a maker that names the virtualization product, an empty unit identifier, a size that no panel has. Everything running inside the virtual machine sees exactly that, and for a program that checks its surroundings it is the plainest possible sign that the environment is virtual. This is why the display identity is part of the hardware identity that the environment shown in this tour presents as a whole: the operating system, the browser and every installed program inside it see the identity of a real monitor, consistent with the graphics adapter, the reported size and the rest of the PC.
What this stop of the tour shows
In this scene the camera moves to the display and opens the identification block as a readable card. The card is a rendering of the fields a real display would report. It is drawn on the page rather than painted into the video, so it stays legible in every language and can be read without the animation. The next stop turns to the system configuration.
| Field | What it says |
|---|---|
| Manufacturer | A short code registered to the maker of the display. A virtual display adapter often reports the virtualization product here. |
| Model | The product code the maker assigned to this panel. |
| Serial | An identifier of this particular unit, stored in the display itself. The field is optional, and some makers leave it empty; virtual displays usually do. |
| Manufacture date | The week and year the panel was made. The week is optional, and a maker may give a model year instead. |
| Physical size | The width and height of the visible area of the panel. Together with the resolution it gives the pixel density that scripts in the browser can see. |
| Preferred timing | The resolution and refresh rate the display asks for by default. |