Hypodermic syringes are medical devices used to inject fluids into the body or withdraw fluids from it. They consist of a cylindrical barrel, a plunger, and a needle. The needle is designed to penetrate the skin, allowing for the delivery of medications, vaccines, or other substances directly into the bloodstream or tissues. These syringes come in various sizes and types, depending on their intended use. They are commonly used in hospitals, clinics, and at home for self-administration of medications. Proper disposal of used syringes is essential to prevent injury and infection, often requiring special containers known as sharps containers.