Is it necessary to salt and drain eggplant for eggplant parmesean?

Im making eggplant parmesean where I have to cut, bread and fry the eggplant before assembling it with the sauce and cheese....Is it necessary to salt and drain the eggplant and if so what is the purpose of this step?
thanks
Update: salt and drain pulls the water out of the eggplant mickey. but for what reason this is necessary Im not sure. thats what im asking.
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