Swollen lymph nodes occur when the lymph nodes, small glands in the immune system, become enlarged. This swelling often indicates that the body is fighting an infection, such as a cold or the flu. Lymph nodes can be found in various areas, including the neck, armpits, and groin. In addition to infections, swollen lymph nodes can result from other conditions, such as autoimmune diseases or cancers. While they are usually not a cause for concern, persistent swelling or accompanying symptoms may require medical evaluation to determine the underlying cause.