Act or ACT may refer to:
An actor (or in some cases actress for females; see terminology) is a person who portrays a character in a performance.
Active Directory (AD) is a directory service that Microsoft developed for Windows domain networks. It is included in most Windows Server operating systems as a set of processes and services.
In physiology, an action potential is a short-lasting event in which the electrical membrane potential of a cell rapidly rises and falls, following a consistent trajectory.
The Acts of Union were two Acts of Parliament: the Union with Scotland Act 1706 passed by the Parliament of England, and the Union with England Act passed in 1707 by the Parliament of Scotland.
Activated carbon, also called activated charcoal, is a form of carbon processed to have small, low-volume pores that increase the surface area available for adsorption or chemical reactions.
The ACT (/eɪ siː tiː/; originally an abbreviation of American College Testing) college readiness assessment is a standardized test for high school achievement and college admissions in the United States produced by ACT, a nonprofit of the same name.
Action film is a film genre in which the protagonist or protagonists end up in a series of challenges that typically include violence, extended fighting, physical feats, and frantic chases.
Actin is a family of globular multi-functional proteins that form microfilaments. It is found in essentially all eukaryotic cells (the only known exception being nematode sperm), where it may be present at a concentration of over 100 μM.
Actinic keratosis (also called solar keratosis and senile keratosis; abbreviated as AK) is a pre-cancerous patch of thick, scaly, or crusty skin.