stdafx header

could anyone tell me what the header "stdafx.h" does?
I searched it up but it does not make sense. From what I read, it simply makes your program compiles faster. Correct me if i'm wrong. Thanks

It is integral to the use of precompiled headers. It usually contains headers that will never normally change (like all the windows api and stdc++ headers). These will be compiled once and then won't need to be continually recompiled every time you make a minor change and compile your project again.