Adenoids (or pharyngeal tonsils, or nasopharyngeal tonsils) are a mass of lymphoid tissue situated at the very back of the nose, in the roof of the nasopharynx, where the nose blends into the mouth. Normally, in children, they make a soft mound in the roof and posterior wall of the nasopharynx, just above and behind the uvula. Adenoids are part of the immune system. Like all lymph tissue, they trap infectious agents like viruses and bacteria, and they produce antibodies.