In chemistry, liquid-liquid extraction is a useful method to separate components (compounds) of a mixture. The success of this method depends upon the difference in solubility of a compound in various solvents.

Liquid-liquid extraction is based on the transfer of a solute substance from one liquid phase into another liquid phase according to the solubility. Extraction becomes a very useful tool if you choose a suitable extraction solvent. You can use extraction to separate a substance selectively from a mixture, or to remove unwanted impurities from a solution.

In the practical use, usually one phase is a water or water-based (aqueous) solution and the other an organic solvent (i.e. vegoil) which is immiscible with water.

In medicine, extraction is the surgical removal of a tooth from the mouth. Simple extractions may be done by a dentist; more complicated extractions are usually performed by an oral surgeon.

In Tactical combat and Special Operations use, extraction is the process of removing constituents from a targeted site when it is considered imperative that they be immediately relocated out of a hostile environment and taken to a Secured Area under friendly control. Extraction may imply the rescuing of entities from grave danger or immediate conditions that they are incapable of surviving within. Both Extraction and Rescue may be for unsuspecting and/or unwilling persons and involving rapid deployment, dynamic defense of the moving tactical envelope and high-speed extrication by a Special Force Protection Team.

In computers, see uncompression.