Virtual machine

A guest system runs on your computer with its own kernel, its own disk and its own network stack. The wall around it is thicker than the one around a browser profile.

If your work needs that wall, use one. Nothing on this page argues against it.

A profile and a guest answer different questions. One separates work places inside a system, the other separates systems.

Everything inside a guest reads the same device, so a second account that must not be linked to the first needs a second guest.

That is where the price shows: a system to keep patched, memory reserved, tens of gigabytes of disk and a boot before the first click.

Two browser windows inside one guest read the same machine as well. Keeping accounts apart in there means running a separate browser for each of them.

These four values are read in the browser you are reading this in. If it runs inside a virtual machine, the renderer line is usually where that shows.

A machine with a card of its own names that card here. A guest usually names a rasterizer instead, and the words in the line are the whole tell.

A guest with no graphics card passed through draws in software, and the renderer names the software rasterizer doing the work. A page reads that line without asking permission.

A browser can be told to report a different line. The drawing itself stays with the machine underneath, because pixels follow whatever draws them.

A rented server tells the same story. Whatever the provider gave that machine is what draws its pictures.

A profile takes its graphics pair from machines that are really sold, and the cores and memory that come with it follow that card.

So a profile does not declare a software rasterizer. What it does not do either is change what draws the picture on the machine you are sitting at.

Cores and memory come from the class of that card. A laptop chip does not arrive with a desktop core count, because the pair is what a check reads first.

A value that no machine of that kind reports is refused rather than applied. A field left alone stays as the profile generated it.

Each of the three separates something different, and choosing by the word alone is how people end up paying twice.

• A browser profile

  Separate storage, exit and readings inside one system, rather than a second system.

• A device farm

  Real hardware instead of software, with the same one identity per unit.

• A remote desktop

  Another machine shown on your screen: a place to work rather than a way to keep accounts apart.