Effect
Effect may refer to:

A result or change of something
List of effects
Cause and effect, an idiom describing causality

Pharmacy and pharmacology
Drug effect, a change resulting from the administration of a drug
Therapeutic effect, a beneficial change in medical condition, often caused by a drug
Adverse effect or side effect, an unwanted change in medical condition caused by a drug

In media
Special effect, an artificial illusion
Sound effect, an artificially created or enhanced sound
Visual effects, artificially created or enhanced images
Audio signal processing
Effects unit, a device used to manipulate electronic sound
Effects pedal, a small device attached to an instrument to modify its sound

Other uses
Effects, one's personal property or belongings
Effects (G.I. Joe), a fictional character in the G.I. Joe universe
Effects (film), a 1979 film (give a wide release in 2005)
Effect size, a measure of the strength of a relationship between two variables
Effect system, formal system which describes the computational effects of computer programs
Pro-Design Effect, an Austrian paraglider design

See also
All pages with titles beginning with Effect 
All pages with titles containing Effect
Affect (disambiguation)
Effectiveness
Efficacy
Pragmatism, the philosophy of causes and effects