Display/Window Managers & Desktop Environments

I'm looking at the #BLFS book and I see that there is the X server #Xorg , various display and window managers plus the more well known desktop environments like #KDE.

The book hints that some of these WM/DMs might be included in things like KDE but I can't seem to figure out which packages I need before following the KDE instructions.

#Linux

I'm fairly confident that I need the Xorg items but I'm not sure if KDE supplies window or display managers.

On a less important side note I notice it mentions #Wayland as an alternative to X in the introduction but then I never see any other instructions for that vs Xorg.

Any advice is appreciated