In general, leaching is the extraction of certain materials from a carrier into a liquid (usually, but not always a solvent). Specifically, it may refer to:
- Leaching (agriculture), the loss of water-soluble plant nutrients from the soil; or applying a small amount of excess irrigation to avoid soil salinity
- Leaching (chemistry), the process of extracting minerals from a solid by dissolving them in a liquid
- Leaching (metallurgy), a widely used extractive metallurgy technique which converts metals into soluble salts in aqueous media
- Dump leaching, an industrial process to extract metals from ore taken directly from the mine and stacked on the leach pad without crushing
- Heap leaching, an industrial process to extract metals from ore which has been crushed into small chunks
- Tank leaching, a hydrometallurgical method of extracting valuable material from ore
- In-situ leaching, a process of recovering minerals such as copper and uranium through boreholes drilled into the deposit
- Leaching (pedology), the loss of mineral and organic solutes due to percolation from soil
- Bioleaching, the extraction of specific metals from their ores through the use of bacteria
- In cooking, leaching generally refers to Parboiling.