A syringe is a medical device used to inject liquids into the body or draw them out. It consists of a hollow tube with a plunger inside that you push or pull, and usually a thin needle attached to the end. When a doctor gives you a vaccine, they use a syringe to inject the medicine under your skin. Nurses use syringes to draw blood samples for testing.

The basic design is simple but powerful: pulling the plunger creates suction that draws liquid into the tube, while pushing it forces liquid out through the needle. Beyond medicine, scientists use syringes in laboratories to measure and transfer tiny amounts of liquids precisely. Veterinarians use them to give medicine to animals. Some syringes don't have needles at all: parents might use a blunt-tipped syringe to give liquid medicine to a baby.

While most people associate syringes with shots at the doctor's office, they're actually one of the most important tools in modern medicine, making it possible to deliver medications directly where they're needed in the body.