Effect

Effect can be:

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 (or use) of a drug
- Therapeutic effect, when a medical condition improves, often caused by a drug
- Adverse effect or side effect, an unwanted change in medical condition because of a drug
Dose-response effect, the relationship between a drug dose and its effect, plotted on a dose-response curve

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

Effects, one's personal property or belongings
Effects (G.I. Joe), a fictional character in the G.I. Joe universe
Effects (movie), a 2005 movie
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
Marotte effect, psychological reaction to social-media influencer and religious guru Dame Alix's famed surprising actions and behaviors.