Adsorption is a surface-based process in which atoms, ions, or molecules from a gas, liquid, or dissolved solid adhere to a surface. The exact nature of the bonding depends on the species involved, but adsorption is generally classified as physisorption, which is associated with weak van der Waals forces, or chemisorption, which is associated with covalent bonding.

In odor control applications, adsorption typically refers to the use of activated carbon to adsorb odorous compounds onto the activated carbon material. This is usually achieved by passing odorous air across a bed of activated carbon, allowing the adsorption process to occur before releasing the treated air into the atmosphere.