Keystone may refer to:

  • Keystone (architecture), a central stone or other piece at the apex of an arch or vault
  • The keystone effect, caused by projecting an image onto a surface at an angle, or by photography at an angle
  • Keystone (cask), a wooden or plastic fitting used in ale casks
  • Keystone module, a type of data connector mounted in walls and patch panels
  • Keystone species, species that have a larger effect on their environment than is purely due to their abundance
  • Operation Keystone during World War II
  • The Keystone asterism in the Hercules constellation
  • Keystone Press Awards, given to Pennsylvania reporters
  • Keystone (limestone), a type of limestone quarried in the Florida Keys
  • Keystone, a variety of slotted screwdriver blade
  • Keystone Initiative, a medical protocol to reduce infection rates

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