03SheerMax

Sup fellas? Couple of weeks ago I started a thread about my 2k3 Auto. My trans was slipping all over the place, as days went by it got worst and worst. My car wouldn't go past second gear, it would just rev and not switch into third. Anyway today I dropped it off to the dealership and found out that I needed a new valve body. I thought maybe I needed a whole new trans, but the service rep told me it was the valve body. Can someone tell me the function of a Valve Body? Thanks