Understanding Internet Cookies: What They Are and How They Track You

What Are Cookies?

Internet cookies are small text files that websites store on your device when you visit them. They are one of the most fundamental technologies of the modern web, enabling everything from keeping you logged in to remembering your shopping cart contents.

First created by Netscape engineer Lou Montulli in 1994, cookies were originally designed to solve a simple problem: HTTP, the protocol that powers the web, is stateless — meaning each request to a server is treated independently with no memory of previous interactions. Cookies provide a mechanism for websites to remember information about your visit.

How Cookies Work

When you visit a website for the first time, the server sends a cookie to your browser along with the web page content. Your browser stores this cookie locally. On subsequent visits, your browser sends the cookie back to the server, allowing the website to recognize you and remember your preferences.

The process step by step:

1. You type a URL and press Enter
2. Your browser sends a request to the website server
3. The server responds with the web page AND a Set-Cookie header
4. Your browser stores the cookie on your device
5. On your next visit, your browser includes the cookie in its request
6. The server reads the cookie and recognizes you

Types of Cookies

First-Party Cookies

First-party cookies are set by the website you are actually visiting. They serve legitimate purposes:

Session cookies

• Temporary cookies that are deleted when you close your browser
• Keep you logged in as you navigate between pages
• Remember items in your shopping cart
• Store form data while you fill out multi-page forms

Persistent cookies

• Remain on your device for a set period (days, weeks, or months)
• Remember your login credentials so you do not have to log in every visit
• Store your language and display preferences
• Remember your cookie consent choices

First-party cookies are generally harmless and essential for websites to function properly. Without them, you would need to log in on every page and your preferences would reset with each visit.

Third-Party Cookies

Third-party cookies are set by domains other than the one you are visiting. They are primarily used for tracking and advertising:

How they work:

• When a website includes content from another domain (ads, social media buttons, analytics), that third-party domain can set cookies
• These cookies follow you across every website that includes content from that same third-party
• By tracking which websites you visit, advertisers build detailed profiles of your interests

Common third-party cookie sources:

• Advertising networks (Google Ads, Facebook Ads)
• Analytics services (Google Analytics, Adobe Analytics)
• Social media widgets (Facebook Like buttons, Twitter share buttons)
• Content delivery networks
• Customer support chat widgets

Supercookies and Zombie Cookies

Beyond standard cookies, some tracking technologies are harder to delete:

Supercookies are stored in different locations than regular cookies, such as:

• Flash Local Shared Objects (Flash cookies)
• HTML5 Web Storage (localStorage and sessionStorage)
• IndexedDB databases
• ETags and cache storage

Zombie cookies regenerate after being deleted:

• They use multiple storage mechanisms simultaneously
• If one copy is deleted, another copy recreates it
• Very difficult to remove completely without specialized tools

How Cookies Track You Across the Web

Here is a practical example of how third-party tracking cookies work:

1. You visit a cooking website that displays ads from AdNetwork
2. AdNetwork sets a cookie in your browser with a unique ID (e.g., user_12345)
3. You later visit a travel website that also uses AdNetwork
4. Your browser sends the same cookie (user_12345) to AdNetwork
5. AdNetwork now knows that user_12345 is interested in cooking AND travel
6. You visit a sports website with AdNetwork ads
7. AdNetwork adds sports to your interest profile
8. AdNetwork now shows you targeted ads based on cooking + travel + sports interests

This process happens automatically across thousands of websites, building an extremely detailed profile without your active knowledge or meaningful consent.

Cookie Laws and Regulations

GDPR (European Union)

The General Data Protection Regulation requires:

• Explicit consent before setting non-essential cookies
• Clear information about what cookies are used and why
• Easy ability to refuse or withdraw consent
• No pre-checked boxes for cookie consent

ePrivacy Directive (Cookie Law)

The EU Cookie Directive specifically addresses cookies:

• Websites must inform users about cookie use
• Consent must be obtained before setting cookies
• Essential cookies (those required for basic functionality) are exempt

CCPA (California)

The California Consumer Privacy Act gives residents:

• The right to know what data is collected
• The right to delete personal data
• The right to opt out of data selling
• The right to non-discrimination for exercising privacy rights

How to Manage Your Cookies

Browser Settings

Every major browser provides cookie management tools:

Chrome: Settings, Privacy and Security, Cookies and other site data

• Block third-party cookies
• Clear cookies when closing the browser
• Block specific websites from setting cookies

Firefox: Settings, Privacy and Security, Cookies and Site Data

• Enhanced Tracking Protection blocks known trackers
• Total Cookie Protection isolates cookies per website
• Options to clear cookies on close

Recommended Cookie Settings

For balanced privacy without breaking website functionality:

1. Block all third-party cookies — This prevents cross-site tracking while keeping first-party functionality intact
2. Clear cookies on browser close — Removes tracking data at the end of each session
3. Use cookie consent tools — When presented with cookie banners, only accept necessary cookies
4. Install a cookie management extension — Automatically handle cookie consent banners

Advanced Privacy Measures

For maximum cookie privacy:

• Use browser containers to isolate different activities
• Enable Total Cookie Protection in Firefox
• Use private/incognito mode for sensitive browsing
• Install extensions that automatically reject cookie consent banners
• Consider DNS-level blocking for known tracking domains

The Future of Cookies

The cookie landscape is changing rapidly:

• Chrome's Privacy Sandbox aims to replace third-party cookies with less invasive tracking alternatives like Topics API
• Server-side tracking moves cookie functionality to the server, making it harder to block
• First-party data strategies — Websites are collecting more data directly rather than relying on third-party cookies
• Privacy-focused browsers are implementing increasingly aggressive anti-tracking measures

Conclusion

Cookies are a fundamental web technology with both legitimate uses and privacy implications. First-party cookies are generally necessary and harmless, enabling basic website functionality and user preferences. Third-party cookies, however, are primarily tracking tools that build detailed profiles of your online behavior without meaningful consent.

By understanding how cookies work and configuring your browser settings appropriately, you can maintain website functionality while significantly reducing unwanted tracking. Block third-party cookies, clear your cookies regularly, and use privacy-focused browser extensions to take control of your online privacy.