Most people have just heard the word dark web but do not really understand what the dark web really is, so I am first going to try and explain what is dark web for those who do not know.
Dark web consists or websites and pages that are not indexed on search engines. For example you search for the term hire a hacker and a lot of search results will come up but there are lots of websites that will never show up on Google or Yahoo or Bing search results and that is what dark web is. It is called dark web due to this reason. You need to know the exact url of the website to be able to reach them.
There is a thriving dark web economy that you can access on such websites. Hiring a hacker is not a problem either but there is no guarantee that you wont be ripped off or scammed in the process because getting hold of a real hacker for hire is not easy as you can imagine due to the nature of work.
You do not necessarily need the dark web if the work you want done is legitimate or even border line as there are plenty of ethical hackers available for hire that you can try.
There could be various reasons people looking for hiring a hacker from securing their devices , computers, phones or servers etc. There are other requirements like getting back their lost accounts etc which do not really require any hacking skills but people have the impression that they need a hacker to to these things where as they can do it all themselves by retrieving their passwords by using different options provided by platforms like Facebook, Snapchat , Instagram etc.
Do let me know if I have left out something or if you would like more information on a particular aspect of dark web although I would personally not recommend hiring a hacker from such platforms.