What is the compact version of Windows 8.1 called?

Question

Microsoft

I remember I came across an article that a new technology was made in tablet Windows, that system files from the distribution are not unpacked, but with the help of special technology they are unzipped into memory on the fly and work in such a way that saves disk space and all that, which is very important in tablets.
I can't find anywhere what this technology is called. Can you please name it, and preferably a couple of links to articles about it.
Thank you.

Answer 1

wimboot?

Answer 2

Probably this is what we are talking about: Booting Windows from a VHD file ( one , two , three )