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Key may refer to:

Common meanings[edit]

  • Cay, also spelled key, a small, low-elevation, sandy island formed on the surface of a coral reef
  • Key (cryptography), a piece of information that controls the operation of a cryptography algorithm
  • Key (engineering), a type of coupling used to transmit rotation between a shaft and an attached item
  • Key (electrical), mechanical component in a plug or socket which prevents mating except with a correctly oriented matching connector
  • Key (lock), a device used to open a lock such as in a door, safe, or other openings to objects or places.
  • Key (map), a guide to a map's symbology


United States[edit]




Art, entertainment, and media[edit]

Fictional characters[edit]

Fictional works[edit]




Other uses[edit]

Visual arts[edit]

  • Chroma key, a method to superimpose several video layers using areas of a defined color as a mask
  • Key frame, a frame made by an animator from which other frames are derived
  • Key light, the primary light source that illuminates an image or scene
  • Key plate, a plate which prints the detail in an image, often using the color black
  • Key color (typically black), in the CMYK color model
  • The primary tone of an image, as in:


  • Samara (fruit) or key, a type of fruit in which a flattened wing of fibrous, papery tissue develops from the ovary wall, often called "helicopters"
  • Identification key, a method of deducing the correct species assignment of a living thing
  • Single-access key, a method used for categorizing species using logical choices

Companies and organizations[edit]

  • Key (company), a Japanese visual novel studio
  • House of Keys, the directly elected lower branch of Tynwald, the parliament of the Isle of Man
  • Key Club, a worldwide student service organization
  • KeyBank, a bank headquartered in the Key Tower in Cleveland, Ohio


  • Superkey, a set of attributes of a relation variable for which it holds that in all relations assigned to that variable
    • Compound key, a set of superkeys that is not minimal
    • Unique key, a superkey in database relational modeling and implementation where there are no two distinct tuples (rows) that have the same values
      • Natural key, a type of unique key found in relational model database design that is formed of attributes that already exist in the real world
  • Primary key, a set of attributes (columns) that uniquely specify a tuple (row) in a relation (table)
    • Foreign key, a field or collection of fields in one table that uniquely identifies a row of another table or the same table
  • Surrogate key, a unique identifier for either an entity in the modeled world or an object in the database




Other uses[edit]

See also[edit]