A lymph node is a small, bean-shaped organ that helps your body fight off germs and illness. You have hundreds of these nodes scattered throughout your body, connected by tiny tubes called lymphatic vessels. They work like security checkpoints in your immune system, filtering out bacteria, viruses, and other harmful substances before they can make you sick.

Lymph nodes contain special white blood cells that attack and destroy invaders. When your body is fighting an infection, nearby lymph nodes often swell up as they work overtime making more of these defender cells. You might notice swollen lymph nodes in your neck when you have a sore throat, or under your jaw when you have a tooth infection. Doctors often check lymph nodes by gently pressing on them during checkups, feeling for swelling that might signal your body is battling something.

Think of lymph nodes as tiny factories that never stop working to keep you healthy, even when you don't notice them. They're part of why a small cut doesn't automatically make you sick: your lymph nodes are constantly filtering out potential threats.