EF or ef may refer to:
The effects of global warming are the environmental and social changes caused (directly or indirectly) by human emissions of greenhouse gases.
The English Football League Championship (often referred to as the Championship for short or the Sky Bet Championship for sponsorship reasons) is the highest division of the English Football League (EFL) and second-highest overall in the English football league system, after the Premier League.
The effects of cannabis are caused by the chemical compounds in the plant, including cannabinoids, such as tetrahydrocannabinol (THC), which is only one of more than 100 different cannabinoids present in the plant.
An effects unit or effects pedal is an electronic or digital device that alters the sound of a musical instrument or other audio source.
Efficient energy use, sometimes simply called energy efficiency, is the goal to reduce the amount of energy required to provide products and services.