The cage effect in chemistry describes how properties of a molecule are affected by its surroundings.

• In a solvent a molecule is often more accurately described existing in a cage of solvent molecules, the so-called solvent cage.
• In a gas at low pressure a normally highly reactive and short lived molecule can be contained.
• specific host-guest interactions occur in inclusion compounds
• Reactions occur when a molecule occasionally "jumps out" and meets another molecule.
• Typical cage lifetime in a solvent cage 10^-11s