Tonsils help guard the body against infection and are considered part of the immune system. They are made out of lymphoid tissue, which creates white blood cells called lymphocytes, or T-cells. These lymphocytes help the body fight off infection. Their job is to fight pathogens that are inhaled or eaten and keep them from spreading to other parts of the body
The throat is actually surrounded by tonsil tissue, but the tonsils most people think of are the palatine tonsils. These can be seen on either side of the back of the mouth and below the roof of the mouth.
Tonsils that aren't so easily seen are the lingual tonsils, which are found at the back of the tongue, the tubal tonsils, which are found at the beginning of the Eustachian tube and the pharyngeal tonsils, which are also known as adenoids and are found at the back of the nose.
The palatine tonsils of children are larger than those of adults. Sometimes, these tonsils become infected to the point where they can block the throat. Though a mild infection can be treated with bed rest and antibiotics, a tonsillectomy might be called for if the tonsils are repeatedly infected.