Comment by falcor84

Thanks for elaborating, it helped a bit and now this section of the Wikipedia article fully clicked for me:

"""The X server is typically the provider of graphics resources and keyboard/mouse events to X clients, meaning that the X server is usually running on the computer in front of a human user, while the X client applications run anywhere on the network and communicate with the user's computer to request the rendering of graphics content and receive events from input devices including keyboards and mice."""