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>>42550 Without going into the full history of the thing...
Nikon's original method of autofocus when they first came out with an AF camera system was to add a motor to the camera body which connects to the lens with a little screw thingy. This let them maintain backwards compatibility with their manual-focus lenses, unlike Minolta and Canon, who came out with full new systems (Maxxum and Eos, respectively) that were incompatible with their old systems.
Eventually, Nikon realized that it was a hell of a lot easier to have the autofocus motor in the lens itself because then you could make the body cheaper (the lenses are the real money makers anyway--Sell the blades, give away the razor) and because it's really difficult to make a one-size-fits-all motor that can drive the autofocus in a little 50mm f/1.8 as well as a 600mm f/4.
So, in addition to the AF lenses (which use the little screw to autofocus), there are AF-S lenses (which just autofocus like Canon lenses by communicating electrically with the motor built into the lens).
The Nikon D40 and D40x are the first Nikon cameras that don't come with an autofocus motor in the body, so while they can still use the AF lenses in manual mode, they can only autofocus if it's an AF-S lens.
So, it has autofocus, but only on some lenses.
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