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14 min read
Explore how websites track users with cookies, pixels, fingerprinting, and server logs—what’s collected, why it’s used, and how to stay compliant.
Simul Sarker
CEO of DataCops
Last Updated
November 20, 2025
The Discovery: I remember first time I opened my browser's developer tools and watched "Network" tab on popular news website. Torrent of requests flooded screen, dozens of cryptic domains firing off in milliseconds it took page to load. I was just trying to read article, but my browser was having frantic, silent conversations with advertisers, data brokers, and analytics companies I had never heard of. Deeper I dug, clearer it became that this invisible data supply chain is far more widespread and complex than most people realize.
The Invisibility: What's wild is how invisible it all is. It shows up in dashboards as "user engagement," in reports as "audience segments," and in headlines about power of big data, yet almost nobody questions intricate and often fragile machinery that makes it all possible. We browse web assuming simple, direct connection between our browser and website we are visiting, but reality is crowded room of eavesdroppers.
The Bigger Question: Maybe this isn't about tracking technology alone. Maybe it says something bigger about how modern internet works and who it's really built for: user, publisher, or vast ecosystem of third parties that operates in spaces between. I don't have all answers. But if you look closely at data flowing from your own browser, you might start to notice it too. This is look under hood at mechanisms that power digital economy.
Most common tracking methods happen on your device, within your web browser.
This is known as client-side tracking, where "client" is your browser (Chrome, Safari, Firefox, etc.).
These techniques form bedrock of web analytics and have been in use for decades.
Oldest and most famous tracking tool is humble HTTP cookie.
Cookie is small text file that website's server asks your browser to store on your computer.
When you return to that site, your browser sends that cookie back, allowing server to remember you.
This simple mechanism is crucial for web to function, enabling:
Keeping you logged into your email
Remembering items in your shopping cart
However, cookies are also primary tool for tracking.
First-Party Cookies:
Created and owned by website you are directly visiting.
Example:
You are on example.com and it sets cookie
That is first-party cookie
Generally seen as trustworthy handshake between you and site
Used to improve your experience
Third-Party Cookies:
Created by domains other than one you are visiting.
Example scenario:
You are on news-website.com
It has ad from ad-network.com
That ad network can ask your browser to store its own cookie
When you visit another-site.com that also uses same ad network
Your browser will send that third-party cookie back to ad-network.com
Result:
Ad network now knows you visited both sites
Allowing it to build profile of your interests
Serve you targeted ads across web
This is foundation of cross-site tracking.
For years, third-party cookies were engine of programmatic advertising.
But their power is waning:
Browsers like Safari and Firefox now block them by default
Google Chrome is phasing them out
Tracking pixel, also known as web beacon, is one of most clever and simple tracking methods.
It is tiny, transparent image, often just 1x1 pixel in size, embedded on webpage or in email.
Invisible to naked eye, but its purpose is not visual.
How it works:
When your browser loads webpage, it has to request all content, including this invisible pixel.
Pixel is not hosted on website you are on. It is hosted on third-party server (like analytics or ad server).
To fetch pixel, your browser sends HTTP request to that server.
This request itself contains valuable data:
Your IP address (reveals approximate location)
URL of page you are viewing
Time pixel was loaded
Information about your browser and operating system (User-Agent string)
This technique is widely used to:
Verify that ad was displayed (an "impression")
Track email open rates
When you get email that says "Your recipient opened this email," it is almost certainly because invisible pixel inside email was loaded from their server.
While cookies and pixels are effective, they are passive.
True workhorse of modern, sophisticated tracking is JavaScript.
Nearly every website you visit runs multiple JavaScript files.
Some are for functionality, like creating interactive menus, but many are for tracking.
JavaScript tracking script, like one used by Google Analytics or DataCops first-party analytics platform, can actively collect vast array of information about your interaction with page.
Far beyond what simple pixel can.
This includes:
Event Tracking:
Which buttons you click
Which videos you play
Which forms you interact with
Engagement Metrics:
How far you scroll down page
Whether browser tab is active or in background
How long you hover your mouse over certain elements
Device and Browser Information:
Your screen resolution
Browser window size
Device type (mobile/desktop)
Installed plugins
Session Reconstruction:
Some advanced tools use JavaScript to record your entire session
Including mouse movements, clicks, and keyboard inputs
Allowing website owners to replay your visit like video to identify user experience issues
Unlike cookie, which is just stored ID:
JavaScript tag is active program running in your browser, constantly observing and reporting back on your behavior.
As browsers and users have become more resistant to traditional client-side tracking, industry has developed more resilient and sometimes more invasive methods.
These techniques move beyond browser's limitations to create more persistent and complete user profiles.
What if website could identify you without using cookies at all?
That is goal of browser fingerprinting.
This technique involves collecting large number of seemingly innocuous settings and attributes from your browser and device.
While each individual data point is not unique, their combination can create "fingerprint" that is statistically unique to you among millions of other users.
Data points used for fingerprinting include:
List of fonts installed on your system
Your precise screen resolution and color depth
Your operating system and browser version
Your language settings and time zone
Specific plugins and extensions you have installed
Subtle differences in how your browser's graphics card renders hidden image (Canvas Fingerprinting)
Resulting hash or ID is highly stable.
Even if you clear your cookies and use private browsing mode, your fingerprint often remains same.
This makes it powerful and controversial method for tracking users who are actively trying to protect their privacy.
Quote from Shoshana Zuboff, Professor Emerita at Harvard Business School, author of The Age of Surveillance Capitalism:
"Surveillance capitalists know everything about us, but their operations are designed to be unknowable to us. They predict our futures for the sake of others' gain, not our own."
This captures essence of techniques like fingerprinting, which operate in background, creating identifiers without user knowledge or consent.
Biggest threat to client-side tracking is client itself: the browser.
Apple's Intelligent Tracking Prevention (ITP), ad blockers, and network-level firewalls can all prevent tracking scripts and pixels from ever reaching their destination.
To circumvent this, many companies are moving to server-side tracking.
Aspect Client-Side Tracking (Traditional) Server-Side Tracking (Modern)
Data Flow User's Browser → Third-Party Server (e.g., Google, Meta) User's Browser → Website's Server → Third-Party Server
Browser Visibility Browser sees and can block requests to many third-party domains Browser only sees request to website's own domain (first-party)
Resilience Low - Easily broken by ITP, ad blockers, and privacy browsers High - Bypasses most client-side blockers as tracking happens on server
Data Control Low - Data sent directly to third parties without moderation High - Website owner can clean, validate, and enrich data before forwarding it
Implementation Simple - Paste JavaScript snippet into website's HTML More complex - Requires server-side container or dedicated solution
With server-side tracking, website takes control of data flow.
Example:
Instead of Meta Pixel on your browser sending conversion event directly to Meta
It sends event to website's own server
That server then securely forwards data to Meta's server
To browser, it just looks like website is talking to itself, so it is not blocked
This is core principle behind modern data integrity solutions.
Example: DataCops platform operates on first-party data collection model.
By having clients point subdomain (like analytics.yourdomain.com) to DataCops servers via CNAME record:
All data collection happens in trusted, first-party context
This makes data stream immune to ITP and most ad blockers
Allowing businesses to reclaim lost data
CNAME Cloaking is specific and controversial server-side technique that has been used by some trackers to disguise their third-party scripts as first-party scripts.
How it works:
Website owner is asked to create subdomain
Point it to tracker's domain using CNAME DNS record
To browser, it looks like legitimate first-party resource
But it is actually third-party tracker in disguise
Privacy-conscious browsers like Safari and Firefox have started to detect and neutralize CNAME cloaking used for cross-site tracking.
This highlights critical distinction:
Using CNAME to create legitimate first-party data pipeline for website owner
Versus using it to deceive browser for third-party's benefit
Solution like DataCops uses CNAME mechanism to establish true first-party context for website owner's own analytics:
Ensuring data ownership and integrity
Fundamentally different goal from third-party tracker hiding its identity
Internet's tracking infrastructure is not just under attack from privacy measures.
It is also being polluted by fraudulent and non-human activity.
This means that even when tracking works, data it collects is often wrong.
It is impossible to overstate impact of Apple's Intelligent Tracking Prevention (ITP) on digital marketing.
On all iPhones, iPads, and Mac computers using Safari:
ITP aggressively restricts lifespan of cookies
Blocks known third-party trackers
With massive market share of Apple devices, this creates huge blind spot in analytics.
Add to this hundreds of millions of users who have installed ad-blocking extensions:
This breaks:
Marketing attribution
Skews performance metrics
Leads to misinformed budget decisions
Other side of crisis is data pollution.
Sophisticated bot networks are designed to mimic human behavior.
They can:
"Click" ads
"Visit" websites
Even "fill out" lead forms
This fraudulent activity has several negative effects:
Inflates website traffic numbers, making site look more popular than it is
Wastes ad budgets on clicks from non-existent users
Pollutes lead databases with fake sign-ups, wasting sales team's time
Standard analytics tools are notoriously bad at distinguishing between real human and advanced bot.
This is why critical part of modern tracking stack is validation layer.
Solutions that provide advanced fraud traffic validation, like DataCops:
Built to analyze traffic patterns
Filter out non-human activity from bots, VPNs, and proxies
Ensuring final data reflects real human behavior
Era of unchecked third-party tracking is ending.
Future of understanding user activity is built on three pillars: data ownership, user consent, and commitment to first-party data.
Quote from Scott Brinker, VP of Platform Ecosystem at HubSpot:
"The solution is not to stop measuring. The solution is to measure better. The move to first-party data isn't just a technical workaround; it's a strategic imperative. It forces brands to build direct relationships with their customers and to be more transparent and responsible with the data they collect."
As Brinker suggests, path forward involves taking control.
Instead of letting dozens of third-party scripts run wild (like multiple messengers all speaking for themselves):
Modern approach consolidates data collection into single, verified pipeline
That speaks on behalf of business
This is difference between:
Using tag manager that just organizes chaos
Implementing true first-party solution that creates order
This approach also integrates seamlessly with consent.
Under regulations like GDPR and CCPA:
Robust tracking system must include Consent Management Platform (CMP) to properly:
Request consent
Store consent
Act upon user consent choices
By building this into core of data collection system, as DataCops does with its TCF-certified CMP:
1. Most tracking happens client-side in browser Cookies, pixels, JavaScript scripts observe and report behavior.
2. Two types of cookies serve different purposes First-party (trusted, from site you visit) vs third-party (cross-site tracking).
3. Tracking pixels are invisible observers 1x1 transparent images send data when loaded from third-party server.
4. JavaScript is most powerful tracking tool Active program in browser collecting events, engagement, device info.
5. Browser fingerprinting works without cookies Combination of browser/device attributes creates unique identifier.
6. Server-side tracking bypasses browser blocks Data flows through website's server, appears as first-party to browser.
7. CNAME can enable legitimate first-party tracking DataCops uses CNAME for true first-party context (not deceptive cloaking).
8. ITP and ad blockers create 20-40% blind spot Apple devices and ad blocker users invisible to traditional tracking.
9. Bot traffic pollutes data with fake signals Sophisticated bots mimic humans, waste budgets, corrupt analytics.
10. Future is first-party, consented, validated Own your data, get consent, filter bots for accurate insights.
If you want accurate tracking of user activity:
Step 1: Understand Current Limitations
20-40% of users invisible to traditional tracking
Bot traffic polluting data
Third-party cookies being phased out
Step 2: Implement First-Party Tracking
Deploy DataCops from your subdomain via CNAME
Bypass ITP and ad blockers
Capture complete user activity
Step 3: Filter Non-Human Traffic
Enable advanced fraud validation
Analyze patterns to identify bots, VPNs, proxies
Ensure data reflects real human behavior only
Step 4: Integrate Consent Management
Use TCF-certified CMP built into DataCops
Properly request and honor user consent
Compliance as feature, not afterthought
Step 5: Consolidate Data Collection
Single verified pipeline instead of multiple messengers
Clean, validate, enrich at source
Distribute to Google, Meta, CRM from one source of truth
Tools: DataCops provides first-party tracking solution that bypasses ITP and ad blockers (CNAME from your subdomain), filters bot traffic (advanced fraud validation), includes TCF-certified CMP (automatic consent compliance), and consolidates data collection (single verified messenger to all platforms).
The bottom line: We started by peering into invisible conversations happening in background of our web browsing. We have seen how that system has evolved from simple cookies to complex server-side architectures, and how it is now cracking under pressure of privacy regulations and data fraud. Fundamental question of "How do websites track user activity?" is shifting. It is no longer just technical question but strategic and ethical one. Old model of passive, pervasive, third-party surveillance is being replaced by new model of active, consented, first-party dialogue. Businesses that succeed in this new era will be those that stop relying on broken and polluted data supply chain. They will be ones that take ownership of their data, invest in systems that ensure its integrity, and build relationships with users based on transparency and trust.
About DataCops: First-party tracking platform that captures complete user activity by serving from your subdomain (bypasses ITP and ad blockers), filtering bot traffic (Human Analytics), and including TCF-certified CMP (automatic consent compliance).
