It really depends how far you go. The basics - they're pretty good. But for the more complicated things they just ignore all context and pretty much restate the names of functions/arguments without explaining how/why things work. See for example https://learn.microsoft.com/en-us/windows/win32/api/tsvirtua... and https://learn.microsoft.com/en-us/windows/win32/api/tsvirtua... What does the terminal services renderer do? "It renders bitmaps you dummy, just look at those arguments!"