Why does voltage arise from the Hall effect?

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Can someone explain the Hall Effect? If electrons are moving inside a magnetic field that is perpendicular to the wire, then perpendicular to both the wire and the magnetic field will be a resultant voltage? Why does this voltage arise?
 

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Do you know about Lorentz force?
Because that basically explains it.

You are driving a current to a slab of material. To be rigorous, let's put the material in the (x,y) plane and let the current flow in the x-direction*. If you also apply a magnetic field in the z-direction, then the electrons that make up the current will experience a Lorentz force. By the basic physical laws, this force acts in the y-direction. So inside the slab, in the direction perpendicular to the currrent, a voltage is building up. After all, this means precisely that on one side electrons "clutter" together and on the other side they become scarcer. This can indeed simply be measured by applying a volt meter across the material in the y-direction.

[small]*) I'm not thinking about directions here: that's a little tricky with the conventions for current flowing in the opposite direction as the actual current carriers, the electrons. I suggest you sit down and work it out for yourself.[/small]
 
The Lorentz force causes the electrons to clutter, which creates a voltage?
 
Well, not really.
It just draws electrons more to one side of the material than to the other side.
So there is more charge on one side than on the other side.
Of course, this is precisely what we mean by a "voltage".