A small piece of data stored in your web browser by websites you visit. While cookies enable useful features like staying logged in, they're also used extensively for tracking your browsing activity across the web for advertising and analytics purposes.

What is Cookie? | Privacy Glossary

Cookies are small text files that websites store in your browser. They're essential for modern web functionality but have become a primary tool for tracking your online activity.

Types of Cookies

First-Party Cookies

Set by the site you're visiting
Enable login sessions, preferences
Generally useful and privacy-respecting

Third-Party Cookies

Set by external domains (advertisers, analytics)
Track you across multiple websites
Primary concern for privacy
Being phased out by browsers

Session Cookies

Deleted when you close browser
Temporary, less privacy concern

Persistent Cookies

Remain until expiration or deletion
Can track long-term behavior

What Cookies Track

Login status
Shopping cart contents
Language preferences
Which ads you've seen
What pages you've visited
Your browsing history across sites
Purchase behavior

The Third-Party Cookie Problem

You visit news.com
  → loads ad from ads.com
  → ads.com sets cookie

You visit shopping.com  
  → loads ad from ads.com
  → ads.com reads cookie
  → knows you were at news.com

Pattern builds across thousands of sites

Protection Strategies

Browser Settings

Block third-party cookies
Clear cookies on close
Use private/incognito mode

Browser Extensions

uBlock Origin blocks trackers
Cookie AutoDelete clears after leaving site

Privacy Browsers

Firefox with Enhanced Tracking Protection
Brave with aggressive blocking
Tor Browser

The Cookie Banner Problem

GDPR requires consent for non-essential cookies, leading to ubiquitous cookie banners. Dark patterns make rejecting harder than accepting.

Beyond Cookies

As cookies get blocked, trackers move to:

Browser fingerprinting
Local storage
First-party tracking (harder to block)

What is Cookie?