To access the dark web a user needs a private network, the most popular of which being Tor. Tor routes all traffic through over 150 different IP addresses per second, and makes tracing any user almost impossible. You can use this browser to access all of the sites on the World Wide Web and remain anonymous, but also to access the dark web. Whereas 'normal' sites have .com or .co.uk, dark web sites are accessed through .onion links. You can't access these through Chrome or Firefox, but Tor can. Once in the browser there are billions of pages which are unique to the dark web, such as Silk Path.
some sites on the dark web have been closed down over the years through intense investigation from authorities such as the FBI, but a version always pops right back up. Silk Path is the successor to the hugely popular Silk Road, shut down only a few years ago. Most sites on the dark web stay up for decades, as it's simply too hard to find the source.
There is a special Wiki devoted to the dark web, as an archive of e-commerce sites available only through Tor or similar. This isn't accessible through normal browsers, but it is conveniently bookmarked in most modern versions of Tor; you cannot search for these sites through Google.
While the dark web did originally start as a hub for illegal activity online, it has been developed into a XXXXXprivate network of users who wish to remain untraced. It's estimated that less than 10% of pages on the dark web are used for illegal activities, while the other 90% is simply people wishing to remain private. With the amount of tracking that goes on on the normal internet, it's not surprising that people have found a way to keep their sense of privacy. Facebook has been shown to use its speech-to-text to listen to people talking and target advertising (Facebook denies this, but it's easily tested). Google tracks where and which Wi-Fi networks a device connects to, making a map of peoples' movements. Even HP has come under fire recently for having low level keyloggers built into their keyboards. There's very little privacy online, and using Tor as your main browser may be slower, but at least the user knows that they're not being snooped on.
The dark web mostly contains one of the largest caches of information in the world, copied from the Web and saved in a form which cannot be limited through ISPs or governments. There are even special search engines for searching the dark web, such as DuckDuckGo Tor. While these do not have the power or resources of Google, they are effective and private.
Some of the websites on the dark web are those which have been banned from the 'normal' internet due to public safety and legal concerns, but that is not always the true reason, though it is often given. Free speech is on the decline on the internet, with Net Neutrality on the rise and policing of message boards. The dark web may well be the future of the internet as we know it today, because it truly is the only place where a user can have complete freedom of speech while remaining anonymous.