system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5:What is a cookie (internet, not delicious food item)?

Also, why's it called a cookie?
gpt
It's a small piece of data that a website sends you and you store on your computer.  Generally used to track something from the server about you.

Good examples of this might be authentication cookies.  The server sends you some information that proves to the server that you're logged in and what account you're logged into.

Bad examples are tracking cookies, which are basically used to see where you go on the internet long term and can be used for everything from targeted ads to more malicious intents.