What is the trailing x

I noticed that their are a lot of technologies that uses X in their names like Directx and PhysX and X server ... is there a something common? Or is th开发者_JS百科ere any reason to choose X?

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According to Wikipedia, the X in DirectX 'stands in' for the various Direct APIs - Direct3D, DirectSound, DirectPlay etc. Seems like a reasonable explanation.

PhysX probably plays on the whole DirectX 'thing' - but I expect it's named as such 'cause it sounds a bit like physics.

X Server serves X. :p

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The meaning of the X varies by usage; in PhysX it seems to be the kewl[sic] way to spell Physics; whereas in X Server (part of the X Window System) takes it's name from being the natural evolution of a system named W (probably short for Window, or just the letter after V; the name of the system on which it ran).

DirectX has already been explained in another answer; so there's that.

But the main reason, most of the time; is that Poor Literacy Is Kewl[sic].