In its simplest form, a microcapsule is a small sphere with a uniform wall around it. The material inside the microcapsule is referred to as the core, internal phase, or fill, whereas the wall is sometimes called shell, coating, wall material, or membrane. Practically, the core may be a crystalline material, a jagged adsorbent particle, an emulsion, a suspension of solids, or a suspension of smaller microcapsules. The microcapsule may even have multiple walls. In this review, only ‘‘core’’ and ‘‘wall’’ will be used to refer to the encapsulated ingredient and encapsulating agent, respectively