A capsule is a type of pharmaceutical dosage form. It is an oral medication consisting of medication enclosed in a small, cylindrical, or oval-shaped container made of gelatin or vegetable cellulose. The medication inside the capsule is in the form of a powder, liquid, or more commonly, a tablet.

There are two types of capsules, hard and soft. Hard capsules consist of two shell halves that fit together and are usually filled with a dry powder or tiny pellets. Soft capsules are made of a single piece of gelatin and are often filled with a liquid medication.

Capsules are commonly used because they have several advantages over other types of dosage forms. One advantage is that they are easy to swallow, and their size and shape can be customized to suit the needs of the patient. Capsules can also be filled with multiple medications or with medications that are incompatible with each other.

Another advantage is that capsules can provide a controlled release of medication over an extended period, they can mask unpleasant tastes or odors, and keep medications stable by protecting them from light and oxygen.

Overall, capsules are a common and widely used form of medication delivery due to their convenience, versatility, and efficacy in delivering various types of medications.