What is the Dark Web? How It Works and Why It Matters

19 February 2025

Most people use the internet daily without realising that what they can see is only a small fraction of what exists online. The part of the internet most people use daily, including news sites, social media, and online shopping, is known as the surface web. Beneath it lies a much larger and less visible layer: the dark web.

The dark web has a reputation shaped largely by dramatic headlines. The reality is more nuanced. Understanding what is the dark web, how it works, and the genuine risks it poses is increasingly important for businesses, IT teams, and individuals who want to stay protected.

How the Internet is Structured

Before exploring the dark web specifically, it helps to understand how the broader internet is divided. There are three distinct layers:

The deep web is far larger than the surface web and is used legitimately every day. It includes anything behind a login. The dark web is a small subset of the deep web, specifically designed to be anonymous and inaccessible through standard means.

What Is the Dark Web?

What's the dark web, exactly? It is a collection of websites and networks that exist on encrypted overlay networks, most commonly accessed using the Tor network (The Onion Router). Tor works by routing internet traffic through a series of volunteer-operated servers around the world, encrypting it at each step. This makes it extremely difficult to trace the origin of the connection or identify the user.

Dark web addresses typically end in .onion rather than .com or .co.uk, and they cannot be found using standard search engines such as Google. They are only accessible through the Tor browser or similar tools.

Key Characteristics of the Dark Web

• Traffic is anonymised through multiple encrypted relay nodes
• Users and website operators are difficult to identify or trace
• It can be accessed from any country, making the jurisdiction complex

What Is Actually on the Dark Web?

The dark web is not exclusively criminal. It contains a broad range of content, some legitimate and some deeply harmful. Understanding this distinction matters, particularly for businesses assessing the risk to their data.

According to the National Crime Agency (NCA), the dark web continues to be a significant enabler of organised cyber crime, including the sale of data stolen from businesses through ransomware attacks and data breaches.

How Does the Dark Web Work?

The Tor network is the primary infrastructure behind the dark web. It was originally developed by the US Naval Research Laboratory as a tool for secure government communications and has since been released as open-source software.

When a user connects to Tor:

• The Tor browser encrypts the connection and routes it through at least three relay nodes (entry, middle, and exit)
• Each node only knows the previous and next hop no single node has full knowledge of the route
• The destination server sees only the exit node's IP address, not the user's real location
• Dark web .onion sites similarly conceal their hosting location, making takedowns difficult

This layered encryption model, hence the term 'onion routing', is what makes the dark web distinctly different from simply using a VPN. A VPN protects browsing on the surface web; Tor enables access to a separate, anonymous network entirely.

Why the Dark Web Matters for UK Businesses

For most businesses, the concern is not about accessing the dark web, it is about what may already be there about them.

When a business experiences a data breach, the stolen data, including customer records, employee credentials, financial details, and intellectual property, frequently ends up for sale on dark web marketplaces. This happens regardless of the business's size or industry. Criminals do not discriminate; small and medium-sized businesses are targeted as frequently as larger enterprises.

Data That Commonly Appears on the Dark Web After a Breach

• Email addresses and passwords (login credentials)
• Credit card and payment card details
• NHS numbers, National Insurance numbers, and passport scans
• Corporate login credentials for Office 365, VPNs, and remote access tools
• Confidential client or customer data
• Internal business documents obtained through ransomware attacks

This is where dark web monitoring becomes directly relevant. Monitoring services scan dark web sources, forums, and marketplaces for any mention of a business's domains, employee email addresses, or known credentials, alerting the organisation before criminals have a chance to exploit the exposure.

What Is Dark Web Monitoring and How Does It Help?

Dark web monitoring is a proactive cybersecurity measure that continuously scans hidden networks, past sites, and criminal marketplaces for data linked to a specific organisation.

What Dark Web Monitoring Typically Detects

• Compromised employee email addresses and passwords from credential dumps
• Business domain names appearing in breach databases
• Credit card details linked to the company
• References to the organisation in criminal forums planning attacks
• Internal documents or files leaked and circulated online

Without monitoring, businesses often remain unaware of an exposure for months, sometimes years. When credentials are stolen and listed on the dark web, attackers typically do not use them immediately. Instead, they may wait, sell them to other criminals, or test them systematically across multiple services.

A managed cyber security service that includes dark web monitoring allows businesses to receive real-time alerts, take immediate action such as resetting compromised passwords, and avoid a breach escalating into a full-scale incident.

What to Do If Your Business Data Appears on the Dark Web

Discovering that business data is being circulated on the dark web can be alarming, but acting quickly reduces the potential damage significantly. The steps below outline an immediate response:

For a more detailed response guide, the blog How to Act on a Dark Web Data Leak covers the full incident response process, including when to involve law enforcement and how to communicate with affected customers.

Staying Protected in a World Where the Dark Web Exists

For businesses, the real concern is not accessing the dark web, but whether company data is already exposed there. Proactive monitoring, strong password security, multi-factor authentication, and rapid response planning all help reduce risk. Renaissance provides dark web monitoring and managed cybersecurity services to help businesses identify and respond to potential exposure before it becomes a larger security issue.

Frequently Asked Questions

Can my business data end up on the dark web?

Yes, and it happens more commonly than many businesses realise. When an organisation experiences a data breach, whether through phishing, ransomware, credential stuffing, or a vulnerability in third-party software, the stolen data frequently ends up listed for sale on dark web marketplaces. This can include employee credentials, client records, payment details, and internal documents.

How would I know if my business data is on the dark web?

Without monitoring, businesses often have no way to know until the data is actively exploited, for example, when a fraudulent transaction is made or an account is taken over. Dark web monitoring services continuously scan known criminal networks and databases, alerting businesses when their data appears. This is now considered a baseline security measure for any business handling sensitive data.

Is it safe to access the dark web?

Accessing the dark web itself is not illegal in the UK, but it carries real security risks. The dark web hosts malicious software, scam sites, and honeypot operations run by both criminals and law enforcement. For businesses, there is no legitimate operational reason to access the dark web directly the appropriate response to dark web threats is monitoring, not exploration.