The so-called explosive electron emission observed as individual packets or avalanches of electrons is shown to occur on microexplosions at the cathode. This avalanche of electrons is called an ecton. Electron current in an ecton starts flowing as a result of the overheating of the metal because of the high energy density (104 J g−1), and the current stops as the emission zone cools off. Ectons occur in plasma-involving phenomena, such as electrical discharges in vacuum, cathode spots of vacuum arcs, volumetric discharges in gases, pseudosparks, coronas, unipolar arcs, etc.