Tonsils are small masses of lymphoid tissue that lie on each side of the throat and that help protect the body against infection; they are part of the lymphatic system.

There are 3 sets of tonsils in the body; 

The lingual tonsils at the level of the tongue.
The palatine tonsil at the level of the hard palate
The pharyngeal tonsil at the level of the pharynx (back of the throat)
Tonsillitis is simply the inflammation of the tonsils due to infection and they are of 2 types; acute and chronic tonsillitis.

ACUTE TONSILLITIS:

This is characterized by abrupt on set of pain in the throat that may radiate to the ear.
Usually resolves within 7-10 days
The tonsil looks red, congested and swollen.
There is difficulty in swallowing due to pain and fever
CHRONIC TONSILLITIS

Also known as recurrent tonsillitis
There are repeated attacks of tonsillitis which result in scarring over crypts.
Presents with halitosis, tiredness, irritation and dryness in the throats.
N/B: Tonsillitis is common among children aged 5-15yrs and occurs more in female than male.

CAUSES

Commonly caused by viral infections and the virus responsible include: adenovirus, Epstein-barr virus, herpes simplex virus, influenza virus.
It is also caused by bacterial infection (streptococcus bacteria)........http://www.medicsjuice.com.ng/2018/08/24/what-you-should-know-about-tonsillitis-see-here/ click link to read full article