system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5:What exactly is the deep web?
gpt
The "deep web" is the term we use to describe web sites and content that aren't indexed by search engines.  

The average internet user accesses content through google, facebook, and other similarly popular platforms. But there's a lot of web content that just isn't (generally) discoverable through these platforms, which is often by design. Many if not most of these sites don't want to be seen by people who don't already know about them.

It's a dark place. Do NOT go there without complete and freshly updated defenses.