It may be known to hackers and coders worldwide but for most internet users, the so-called 'Deep Web' remains shrouded in mystery, a supposed morass of drugs, deviancy and stolen credit card details.
Interest in this massive part of the Internet - which is inaccessible by search engines and includes blocked sites, limited-access networks and private sites that require login credentials - has piqued in recent years, especially following the 2013 FBI investigation into online marketplace Silk Road that exposed the extent of online drug trafficking. The hit television series House of Cards also featured the phenomenon during its second season.
Now, security software firm Trend Micro has explored the anatomy of the Deep Web, investigating why people go there and the wide range of their transactions. Want to go deeper into the Deep Web? Trend Micro's report has the answers to your key questions.
It's around 400 times larger than the visible Web, according to the report. The nature of the Deep Web makes an accurate estimation of size impossible but over the course of two years, Trend Micro collected more than 38 million pieces of content that account for 576,000 URLs.
English language sites make up the bulk of the Deep Web at 62 percent. Russian was second at nearly 7 percent, followed by French at 5.5 percent.
Logging on to the Deep Web requires the use of specific software that allows users to communicate anonymously, such as TOR, Freenet, or the Invisible Internet Project, the report said. A brief Google search reveals that TOR is easily available and free, making access relatively simple.
The biggest advantage of the Deep Web is anonymity; users cannot be tracked by Internet Protocol (IP) addresses or physical locations. Such high levels of privacy are typically conducive to illegal purchases of drugs, firearms, identification, credit cards and even contract killers.
For $782, users can purchase an American passport, the priciest nationality to obtain, or $446 for Brazilian citizenship, the cheapest. Hiring a hitman costs $45,000 if you want a "low-ranking" individual killed, compared to $180,000 for a "high-rank and political" figure.
But, contrary to public opinion, it's not all criminal activity, Trend Micro notes.
"People who want to shield their communications from government surveillance may also require the cover of darknets. Whistleblowers may want to share vast amounts of insider information to journalists without leaving a paper trail. Dissidents in restrictive regimes may need anonymity in order to safely let the world know what's happening in their country ," the report said.
Bitcoin is usually the currency of choice for purchasing illicit goods and services, the report said.
"By mixing Bitcoins-transferring them through a spidery network of microtransactions before returning them- you end up with the same amount of money (minus a small handling fee) but your transactions become substantially harder to track."
Aside from hosting a thriving black market economy, the Deep Web is also home to malware like computer viruses, trojan horses and spyware.
Data protection and hacking are now key concerns for governments and corporations following a spate of high-profile attacks, so being aware of malicious programs on the Deep Web is crucial for installing solid security software.
Doxing, the act of broadcasting an individual's personally identifiable information (PII) like social security numbers and physical addresses, is also a common phenomenon, Trend Micro said, reporting that it found information on public figures like Barack Obama, Hillary Clinton and various celebrities during its research.
During the Silk Road trial, several news reports conflicted on whether the site belonged to the Deep Web or the Dark Web, creating confusion on whether the terms 'dark' and 'deep' were interchangeable.
They are not, explains Trend Micro: "The Dark Web is only part of the Deep Web. It relies on darknets or networks where connections are made between trusted peers."
The Silk Road site was indeed part of the Dark Web, and the majority of public interest in the overall Deep Web lies in activities that happen inside these darknets as they are harder to access, the report added.