Capsules are solid dosage forms that enclose medicinal or inert substances within a soluble shell, usually made of gelatin. There are two main types: hard gelatin capsules and soft gelatin capsules. Hard capsules have two cylindrical sections that are joined together, while soft capsules are one-piece shells containing liquids or semisolids. Capsules offer advantages like rapid drug release, flexibility in formulation, and taste masking, but have disadvantages related to size limitations, moisture control issues, and potential difficulty swallowing large sizes. Quality control tests evaluate attributes like shape, size, disintegration time, and drug content uniformity.