Microencapsulation is the process of enclosing a substance inside a miniature capsule. Such capsules are called microcapsules. The substance inside the microcapsule is usually a solid or a liquid, though a gas may also be used. The capsule wall is made of gelatin, wax, or another natural substance, or of plastic.
Microencapsulation is used to make scratch-and-sniff stickers and perfume strips used in advertisements. When a person scratches the sticker or perfume strip, some of the microcapsules break, releasing a scent.
Some microcapsules are designed to deliver chemicals slowly over time. They help regulate the release in the body of aspirin and other drugs. By using a single application of microencapsulated pesticides, a farmer can control weed growth or kill harmful insects for up to several months.