The deep web is a relatively unexplored place that is not accessed by search engines. Consider it like another realm, beyond the borders of the regular, clean internet. It does have some useful stuff, but most of it is dark web. This part contains twisted texts, videos, pornography and weird content that will leave you stunned. In addition, it is not safe to access as it is crawling with viruses and hackers.
You can easily lose your device if you are not experienced in protection. Moreover, you can be scammed, hacked or can even end up in jail. You will not end up in prison simply for accessing it, but most of the dark web is used for illegal purposes that can lead to prison.