I have very low water pressure in my kitchen and the up stairs bathroom but the water pressure in the basement is good.

I have very low water pressure in my kitchen and the up stairs bathroom but the water pressure in the basement is good. I need more details!
Is the pressure down on both hot and cold? What type of pipes do you have? Copper, plastic or galvanized? Have you renoved the aerators and checked the pressure then? Are all fixtures in your bathroom affected? Talk to me! Tom