Tonsils face a lot of bacteria and viruses, making them a playground for some infective agents, so it’s common for them to get infected causing tonsillitis.
Tonsillitis happens when the tonsils are overwhelmed by viruses or germs, and is essentially the inflammation of the lymph nodes, and it’s the Palatine tonsils that usually get the brunt of it.
Due to their location in the body, the Palatine tonsils visibly swell up, causing issues in that area. Those issues include the feeling of a sore throat, coughing, pain when swallowing, fever, and headaches.
This infection tends to happen more in children than adults. That’s due to them being exposed to germs in the outside world such as in schools, playgrounds, and from other children who already have it.