Physical DVD drives might be an endangered species on PCs, but they live on in virtual format, thanks to ISO disk image files.
ISO files are a common way to distribute software that would previously have required a DVD. When you use the Windows 10 Media Creation Tool, for example, one of two default options is to save the installer as an ISO file.
In Windows 7 and earlier, the only thing you could do with an ISO file was burn it to a DVD. For any other task, you needed third-party software. In Windows 10 (as with Windows 8.x), you can simply double-click an ISO file to mount it as a virtual DVD drive.
That virtual drive shows up in File Explorer with its own drive letter, and it acts just like a DVD. You can copy files from the virtual DVD to any other storage medium, for example. If the ISO file contains installation media you can run Setup directly, without the tedious step of extracting files.
One feature that isn’t obvious right away is how to unmount a virtual DVD. Mac users will probably figure it out instantly, but for longtime Windows users here’s the answer: Right-click the virtual DVD in File Explorer and then click Eject.