The electric effect can be classified into two types, namely the +E effect and the -E effect. This classification is based on the direction of electron pair transfer. When the attacking reagent is electrophile, the +E effect is generally observed and π-electrons are transferred to the positively charged atom. When the attacking reagent is a nucleophile, there is generally an -E effect, where π electrons are transferred to atoms to which the attacking reagent will not bind.