Most people will never have heard of the area of the internet called the dark, hidden or deep web.
And that should hardly be surprising - after all it is not accessible through your everyday web browser, such as Microsoft Explorer, Google Chrome or Mozilla Firefox.
You won’t be able to find it unless you go looking for it.
But references to the cyber underworld are starting increasingly to creep into everyday life, whether that be through popular culture such as in TV shows like American Netflix hit House of Cards or through warnings from crime enforcement agencies and governments.
The use of the word ‘dark’ references the sinister side of this online world, where marketplaces have been uncovered for the trading of drugs, weapons, fake ID documents, indecent images of children and sex workers, using digital currency known as ‘bitcoins’.
This international economy can thrive as a result of the anonymity offered by the dark web, and responsibility for breaking it up in the UK falls to the National Crime Agency (NCA), which also runs the Child Exploitation and Online Protection Centre (CEOP).
So what is this hidden area of the internet? It isn’t anything new, but thanks to arrival of popular world wide web browsers in the early 1990s it was no longer explored. Experts estimate that it is in fact larger than the ‘non-hidden’ internet.
An NSA spokesman said: “The most common way of entering the dark web is through Tor - free software which when downloaded allows you to search the internet and be anonymous while doing so by concealing your location.
“This didn’t start out as a criminal enterprise and we are not here to demonise all use of it. What we are interested in is when it is used to conduct criminal activities.”One of the most famous web sites dealing with illegal commodities is Silk Road, where users can buy illicit goods. It includes a drugs market selling everything from legal highs to class A substances.
The original Silk Road site was shut down by the FBI in autumn last year, but soon after Silk Road 2.0 appeared and another after that.
“When you remove one site you are simply taking out a server housing that - an internet address - but you can rehash that, another server can launch it instead and it reappears,” the NCA spokesman said.
“We have seen a growth in sales in recent years on sites like Silk Road but there is a very good chance that goods are not what they claim to be.
“All our investigations take a significant period of time and the anonymity offered to individuals in this crime just means it takes a little longer.
“These online market places are effectively organised crime networks, even if the individuals do not know who they are dealing with.
“We know more sites tend to be set up but we will get faster and more effective in shutting them down and finding those responsible as our understanding grows.
“You are not likely to come across the dark web unless you go looking for it and if you do you should be very careful because you will leave yourself open to criminals who will look to exploit you.”
Last month, the NCA announced that coordinated activity by law enforcement in Europe and the US had resulted in the arrests of six people on home soil, with suspects including the alleged administrators for the online drug market place Silk Road 2.0 and another drug market place, as well as significant vendors of illegal drugs through the dark web.
Simultaneously, partners from the European Cybercrime Centre took out technical infrastructure key to hosting illegal market places on the dark web. In total, more than 400 dark web sites were taken down.
Roy McComb, NCA deputy director, said: “Over the months since the original Silk Road was taken down, we have been working with partners in the US and Europe to locate technical infrastructure, key to the dark web and to investigate individuals suspected of significant involvement in illegal online market places.
“Those arrested by the NCA in this phase of the operation are suspected of setting up Silk Road 2.0, or of being significant vendors of illegal drugs.
“The operation is ongoing and more arrests can be expected as we continue to investigate those involved in setting up and profiting from these illegal market places.
“Criminals like to think that the dark web provides a safe, anonymous haven but in reality this is just like any other organised crime network.”
In the North East, it is the job of local police forces to act on the evidence provided by the NCA and CEOP.
Northumbria Police said they were aware of the ‘dark web’ and were investigating any reported incidents linked to it.
And Detective Sergeant Steve Days is Durham Constabulary’s hi-tech crime unit manager, operating out of Chester-le-Street. He is keen to refer to the encrypted world as the deep web.
He said: “Pretty much 100 per cent of deep web related cases we are involved in are suspected paedophiles, through grooming and sharing indecent images.
“The more the deep web is publicised the more underground these offenders will look to go to offer them anonymity.
“It is my view that these people acting illegally will always will drop the ball at some point and we will be there to catch them. All it takes is for one paedophile to be caught and we can trace all their contacts.
“Yes, we may be waiting for them to make mistakes but we also have innovative techniques and technology at our disposal.”
He added: “The internet is massive and conventional search engines like Google only explore a fraction of it.
“I don’t like the name ‘dark web’ being given to the rest of it because in reality it is not all sinister - much of what goes on there is lawful.”
So if people are not accessing this world with criminal intentions, why are they?
Dr Stacy Gillis, a lecturer at Newcastle University’s School of English, claims a focus on criminal activities in the hidden web distracts people from a more important debate.
She explained: “A great deal is made of transactions that are criminal, with Silk Road being the most well-known in terms of trading drugs, child pornography and trafficking, and arms - the three areas generally viewed as the drivers of the dark web - but I am not convinced that is all there is to it.
“There is a growing interest in anonymity and the dark web does render you anonymous as you browse the web.
“A couple of years ago I was researching an article on cyber sex in my previous workplace and I typed it into my browser. I got into serious trouble as a result, because I was under surveillance and was being restricted in what I could do.
“I don’t think being on the web anonymously is such a bad thing. I know a number of people who use the dark web and they just don’t like that feeling of surveillance - they are not interested in purchasing drugs or looking for Kalashnikovs.”
She added: “In an era of Edward Snowden, the NSA and Julien Assange, there is a culture of people questioning why they are being put under surveillance. What is it that makes it OK for the state to do this?
“As a result the dark web has become a holding space for all our fears about the internet and there has always been fear of technology, but the reality is that crime manages to populate new space geographically or digitally remarkably easily.
“The debate is focusing on crime and is being moved away from a discussion on why governments can track internet activity.”