Tonsil is a small mass of lymphatic tissue sit at the posterior of the throat in human. This term is used to designate any of three sets of tonsils but most commonly refers to palatine tonsils. The palatine tonsils are two oval-shaped lymphatic tissue masses from each side of the oral pharynx. Each tonsil has numerous pits on the surface that lead to deeper lymphatic tissue. With these rich lymphatic tissues, the palatine tonsils are thought to play a key role in preventing infection in the respiratory and digestive tracts. Pharyngeal tonsils (also known as adenoids) are another major tonsil pair, which are diffuse masses of lymphatic tissue situated at the top wall of the nasal pharynx. Enlargement of these tonsils may block breathing through the nose and result in the sinus or middle ear infections. The third pair of tonsils is lingual tonsils located at the base of the tongue. It is kind of aggregations of lymphatic tissue. Tonsils are prone to get an infection while injured or the immunity of the body decreased, and a surgical removal may be required. A variety of target molecules on tonsils are used to detect the related disorders.