system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do we have tonsils?
gpt
Tonsils are lymphatic tissue, meaning tissue that is responsible for capturing, sequestering, and destroying infectious agents. The places in your body that have the most lymphatic tissue are the places that are the easiest to infect through. Your mouth is what you use to eat and breathe, daily, and so your tonsils are located right there at the back of your throat, as prisons and death rows for anything that tries to infect you through your mouth and throat. 

By the way, the tonsils that we think of as "tonsils" are actually not the only ones. Those are the palatine tonsils. There are also lingual tonsils (which sit on the back of the tongue and look like really big taste buds) and also pharyngeal tonsils (which are at the top of the throat, where the nasal cavity ends). Those guys typically don't get as swollen or infected as the palatine tonsils, and so they're almost never removed.