An electric spark is a type of electrostatic discharge that occurs when an electric field creates an ionized electrically conductive channel in air producing a brief emission of light and sound. A spark is formed when the electric field strength exceeds the dielectric field strength of air. This causes an increase in the number of free electrons and ions in the air, temporarily causing the air to become an electrical conductor through dielectric breakdown.
Lightning is an example of an electric spark in nature, while electric sparks, large or small, occur in or near many man-made objects, both by design and sometimes by accident.
A continuous discharge of electric current through a gas is an electric arc.