Electrophilic addition is a chemical reaction where an electrophile reacts with a nucleophile, resulting in the formation of a new bond. This reaction is significant in organometallic chemistry as it allows for the incorporation of new groups into organic molecules, often altering their reactivity and properties. Electrophilic addition plays a vital role in synthesizing various compounds by facilitating the transformation of alkenes and alkynes through interactions with electron-rich species.