Broadly speaking, an effect can be any component of the picture or sound that is not a simple production element and is specially created to imitate a natural or unnatural event or otherwise produce some unusual response within the audience.

They can be a part of production (makeup effects, for example) or added later in post-production, as are many sound effects and visual effects (dissolves and fades, for example). Effects for both video and film can be grouped together into sound/audio effects and image effects.



Film Video Terms and Concepts Steven E. Browne, Focal Press, 1992