Hair color help/advice?

I have naturally blond hair but have been dying it a medium brown color since about Christmas. I miss my natural color, so I called my hairdresser and asked if it is possible to strip or rinse the color out. She said it would dry it out too much, and suggested I do a partial foil to lighten it instead, and then when it grows back it will blend better with my roots. Does anyone have a partial foil? What is it? Do you like it? Can you post me a picture? I am afraid it will be bleachy-blond. Is bleach used in a foil? Help!