Normal aircrafts can be described as fly by cables and pulleys. Lowest FBW, the inputs on the side sick (Airbus) or yoke( boeing) are converted into elctrical signals which are carried by electric wires to flight control servoes. However once you get into electrics it is possible to involve computers to modify the pilot demand. This are called protections, they can be soft (777) where pilot can override them or hard where he cannot even if he wants to (Airbus). This is basic.