This chapter describes the use of external-electric fields (EEFs) as effectors of chemical change{,} with the aim of providing a guiding conceptual framework. As such{,} the following text intends to serve as a teaching material for readers{,} on how to conceptualize and design electric-field effects on bonds{,} structures{,} and reactions. Many of these effects can be comprehended in terms of valence bond (VB) concepts as the field-induced stabilization of ionic structures. Thus{,} orienting the field along the “bond axis” will facilitate bond breaking. Similarly{,} orienting the field along the “reaction axis”{,} the direction in which electron pairs transform from reactant-to product-like{,} will lower the reaction barrier. Flipping the field{'}s orientation along the reaction axis will cause inhibition. Orienting the field off-reaction-axis will generally control stereo-selectivity and enantioselectivity{,} and the removal of forbidden-orbital mixing. Three-directional fields will orient the reactants in space and control their reactivity and selectivity patterns. Increasing the field strength for concerted reactions{,} e.g.{,} in Diels–Alder and oxidative addition reactions{,} will cause mechanistic-switchover to stepwise mechanisms with ionic intermediates. Examples of bond breaking and control of reactivity/selectivity and mechanistic crossovers are presented and analysed from the “ionic perspective”. Textboxes and rules summarize the various effects of electric fields.